1. Research is:(a) A fault activity(b) An activity that helps in development(c) An interesting activity(d) An activity that adds to happiness of the people2. A researcher should always:(a) Know everything in his area(b) Know about sub-area(c) Wait for an inspiration(d) None of the above3. Which of the following best sums up the objective of hypothesis?(a) It places clear goals for the researcher(b) It prevents the researcher from undertaking blind research(c) It enables the researcher to draw conclusions.(d) It lays down the rules for undertaking the research4. One undertakes research for which of the following purpose?{a) To verify what has been established(b) To refute some assumptions(c) To describe a new phenomenon(d) Either of a, b or c5. Research promises advancement of knowledge but discoveries are rare bee(a) Research is a critical, continuous investigation(b) Researchers are not creative enough to solve problems(c) Sustained effort at research is lacking these days(d) Most people lack the aptitude for research6. Language is a(a) Instinctive development(b) System of symbols for effective communication(c) Medium to express experiences(d) Medium for self enhancement7. An individual's ability to learn is(a) Absorbed(b) Acquired(c) Occurring from within(d) Developed8. Bibliography given in a research report(a) Helps those interested in further research and studying the problem from a angle.(b) Shows the vast knowledge of the researcher(c) Makes the report authentic(d) None of the above9. The research antagonistic to ex-post facto research is(a) Experimental studies»(b) Library researches(c) Normative researches(d) all of the above10. An example of scientific knowledge is(a) Social traditions and customs(b) Authority of the prophet or great men

(c) Religious scriptures(d) Laboratory and field experiments11. The process not needed in experimental researches is(a) Controlling(b) Observation(c) Manipulation and replication(d) Reference collection12. Research promises advancement of knowledge but discoveries are rare because:(a) Research is a critical, continuous investigation(b) Researchers are not creative enough to solve problems(c) Sustained effort at research is lacking these days(d) Most people lack the aptitude for research13. In any discipline, theories and observations (related experiment results):(a) Should complement each other(b) more often than not should contradict each other(c) Need not have anything to do with each other(d) should compensate each other14. If I do not get a satisfactory explanation to certain occurrences.(a) It may not be worth knowing at all(b) It would be better to wait for a person who can explain it(c) It would be better to visit a nearby research institute to get more information(d) I would not be at rest till I get a correct explanation15. All are example of qualitative variables except(a) Sex(b) Religion and castes(c) Observation(d) Interest of the subject16. If the sample drawn does not specify any condition about the parameter of the population, it is called(a) Selected statistics(b) Distribution free statistics(c) Census(d) Non of the above17. Attributes of objects, events of things which can be measured are called(a) Data(b) Qualitative measure(c) Variables(d) None of the above18. In order to augment the accuracy of the study a researcher(a) Should be honest and unbiased(b) Should increase the size of the sample(c) Should kept the variance high(d) all of these19. Hypothesis cannot be stated in(a) Declarative terms(b) Null and question form terms(c) General terms(d) Directional terms20. All causes non sampling errors except

(a) Faulty tools of measurement(b) Inadequate sample(c) Defect in data collection(d) Non-response21. Formulation of hypothesis may not be necessary in(a) Survey studies(b) Fact finding (historical) studio(c) Experimental studies(d) Normative studies22. Who is regarded the father of scientific social surveys?(a) Best(b) Booth(c) Darwin(d) None of these23. A good piece of research is a product of:(a) Collective scholarship(b) a good library(c) A penetrating and analytical mind(d) a touch of genius24. What is statistical inference?(a) Reaching conclusions from a sample(b) Analyzing statistical data(c) Applying statistical methods(d) Developing statistical theories25. Which of the following is not correct? A belief becomes a scientific truth when(a) Is established experimentally(b) Is arrived logically(c) Is accepted by many people(d) can be replicated26. The experimental study is based on the law of(a) Single variable(b) Occupation(c) Replication(d) interest of the subject27. Fordoing external criticism (for establishing the authenticity of tin a) a rese must verify(a) Signature and handwriting of the author(b) The paper and ink used in that period which is under study(c) Style of prose writing of that period(d) all of the above28. Survey study aims at(i) Knowing facts about the existing situation(ii) Comparing the present status with the standard norms(iii) Criticizing the existing situation(iv) Identifying the means of improving the existing situation(a) (i) And (ii) only(b) (i), (ii). And (iv)(c) (i), (ii), (iii) And (iv)(d) (ii) And (iii) only29. Which of the following is not the characteristic of a researcher?

(a) He is industrious and persistent on the trial of discovery(b) He is a specialist rather than a generalist(c) He is not inspirational to his chosen field but accepts the reality(d) He is not versatile in his interest and even in his native abilities(e) He is versatile in his interest even in his native abilities(f) He is objective30. The validity and reliability of a research will be at stake when -(a) The incident was reported after a long period of time from that of its occurrence(b) The author who is the source of information is biased, incompetent of dishonest(c) The researcher himself is not competent enough to draw logical conclusions(d) All of the above31.A researcher wants to study the future of the Congress I in India. For the study which tool is mostappropriate for him?(a)Picnics/excursions(b)mock-parliament(c)Celebration of festivals(d)all of the above32. seeing a very big it was reported that JD will win the election, the conclusion was based on(a) Random sampling(b) Cluster sampling(c) Purposive sampling(d) Systematic sampling33. A researcher divides his population into certain groups and fixes the size of the sample from eachgroup. It is called(a) Stratified sample(b) Quota sample(c) Cluster sample(d) all of the above34. Which technique is generally followed when the population is finite?(a) Purposive sampling technique(b) Area sampling technique(c) Systematic sampling technique(d) None of the above35. Which of the following is a non-probability sample?(a) Quota sample(b) Simple random sample(c) Purposive sample(d) (a) and (c) both36. A researcher selects a probability sample of 100 out of the total population. It is(a) Cluster sample(b) A random sample(c) A systematic sample(d) A stratified sample37. A good hypothesis should be

(a) Formulated in such a way that it can be tested by the data(b) Precise, specific and consistent with most known facts(c) Of limited scope and should not have global significance {d) all o these38. While writing research report a researcher(a) Must arrange it in logical, topical and chronological order(b) Must not use the numerical figures in numbers in the beginning of sentences(c) Must compare his results with those of the other studies(d) all of the above39. Which of the following is a primary source of data?(a) Official records - governments documents, information preserved by social religious organization etc.(b) Personal records, letters, diaries, autobiographies, wills, etc.(c) Oral survey of traditions and customs(d) All of the above40.A farmer considers the age-old method of ploughing better then the latest methods available to him.In arriving at this conclusion, he is being influenced by: «(a)Tradition(b)Experience(c)Reason(d)Experimentation41.Consider the following statement: 'Observations, in themselves, are of little statement.' What is thebasis of making such a statement?(a)They are without any purpose(b)They must be related to other facts for generalization(c)They are not systematic and not amenable to scientific interpretation(d)They are meaningful only if collected by a scientist42.(a)(b)(c)Logic of induction is very close toThe logic of samplingThe logic of the controlled variableThe logic of observation(d) none of the above43. Field study is related to(a) Real life situations(b) Laboratory situations(c) Experimental situations

(d) None of the above44.A researcher divides the populations into PG, graduates and 10+2 students and using the random digittable he selects some of them from each. This is technically called.(a)Settled sampling(b)Stratified random sampling(c)Representative sampling(d)None of these45. Generalized conclusion on the basis of a sample is technically known as(a) Statistical inference of external validity of the research(b) Parameter inference(c) Data analysis and interpretation(d) all of the above46. Validity of a research can be improved by(a) Taking the true representative sample of the population(b) Eliminating extraneous factors(c) %(d) Both the above measures   None of these47. In higher education, research and education are two activities that:(a) Cannot go together(b) Can go only in sequential order(c) Can go together(d) Can go together but at the expense of each other48. for a proposition to be true, it is necessary that it should have all of the following excepts:(a) It must be objective(b) It must be in tune with accepted beliefs(c) It must be consistent(d) It must be testable49. Which of the following is not the requirement of a hypothesis? It should:(a) Be based on facts(b) Be conceivable(c) Contradict the knowledge of nature(d) Allow consequences to be deducted from it50. Which of the following is most reasonable about teaching and research activities?(a) Both are entirely different activities(b) Both cannot be done side by side(c) Both are two aspects of the same coin(d) Both could hinder one another51. My reaction to the statement: "A good teacher is essentially a good researcher" is that this is:(a) My firm belief(b)(c)(d)Difficult to agree to

It is an opinionOnly a hypothesis52.The first question that a researcher interested in applying statistical techniques to his problem has toask is:(a)Whether data could be qualified or quantified(b)Whether appropriate statistical techniques are available(c)Whether analysis of data would be possible(d)Whether worthwhile inferences could be drawn53.The main difference between an administrator and researcher lies in the fact that:(a)The former is more concerned only with the what of things while the researcher is interested in boththe what and why of things.(b)The former approaches problems in a practical manner while the later is purely theoretical(c)The former takes a global view while the later penetrates deep into specific issues(d)The former is more interested in social outcomes while the later in finding out as to why things happenas they do.54. Which would be acceptable for establishing a fact?(a) Opinion of a large number of people(b) Traditional practice over a lone period of time(c) Availability of observable evidence(d) reference in ancient literature55. Research aim at:(a) Control of concerned matter(b) Understanding of concerned matter(c) Human welfare with help of concerned matter(d) Prediction of concerned matter56.`The research supervisors require the following as essential qualities:(a) `Expertise of subject matter(b) `Methodological(c) `Interdisciplinary(d) `Which is true(i) ``Only A(ii) `Only B(III) Both A & B(iv) `All57.(a)(b)(c)(d)

A good research always begins with:An original ideaPreparation of plan and design for studyStudy of relevant research methodologyReview of literature58.In every field research promotes systematic and gradual advancement of knowledg but still discoveriesare rare:(a)It requires a continuous critical investigation(b)Experimental work needed for discovery is not easily forthcoming(c)Most people lack depth of knowledge for it(d)Not able to think beyond a point59. Sin - qua- non of good research is:(a) Well formulated hypothesis(b) Good research supervisor60. Which of the following is not a quality of scientific research?(a) Imagination(b) Creativity(C) Objectivity(d) Subjectivity61. Objectivity in research implies:(a) Correct judgment of truth(b) Finding consistency with reality(c) Research - researcher agreement(d) Methodological sophistication62. One undertakes research:(a) To verify what has already been established(b) To refute what has already been accepted as a fact(c) To describe and explain a new phenomenon(d) one or more of above63. The valid base of knowledge lies in:(a) Customs and traditions(b) Authority(c) Scientific enquiry(d) Personal experience64. Research process and scientific thinking are(a) Unrelated process(b) Process of enquiring new knowledge with different emphasis(c) Synonymous(d) Similar in some situations and dissimilar in others65. Building up of theory is the aim of:(a) Action research(b) Fundamental research(c) Historical research(d) Applied research

66. Action research has its origin in:(a) Modern human organization & theory(b) System approach to education(c) Logical thinking process(d) Educational technology67. Random sampling doesn't:(a) Make the sample: representative of population(b) Ensure generalization of result(c) Reduce error and increase precision of experiment(d) Maximum experimental variance68. Which one of the variable is not discrete variable?(a) Age(b) Company bonds(c) Place of residence(d) Sex69. For a proposition to be true, it is necessary that it should have all of the followings:(a) It must be objective(b) It must be consistent(c) It must be testable(d) It must be in tune with accepted beliefs70. What is not correct?(a) A beliel becomes a scientific truth when it is established experimentally(b) It is arrived at logically(c) It is accepted by many people(d) It can be replicated71. from the following qualities which are essential for research scientists:(a) Keenness(b) Persistence(c) Faith(d) Logical reasoning72. What is statistical inference?(a) Reaching conclusion from a sample(b) Analyzing statistical data(c) Applying statistical methods(d) Developing statistical theories73. Sample is to population as:(a) Large: Small(b) False: True(c) Part: Whole(d) Commerce: Science74. The process from where one proceeds from some given truth to an unknown truth is:(a) Stating a conclusion(b) Stating a premise(c) Making a judment(d) Making a inference75. Qualitative research differs from quantitative research as it:(a) Views phenomenon in a holistic manner(b) Uses survey instead of experimentation(c) It is cross sectional in nature

(d) It is highly objective76. Two variables are correlated:(a) If with the change in one variable other variable also changes(b) Change of variables are in opposite direction.(c) "Two variables are similar in nature(d) Two variables are dissimilar77. The sampling design the purpose of which is to reduce per unit cost:(a) Simple random(b) Cluster(c) Systematic(d) Stratified

ANSWERS

(1) b (2) b (3) a (4) d (5) a (6) c (7) c (8) a (9) a (10) d (11) d (12) a (13) a (14) d (15) d (16) b (17) c (18) d (19) c (20) b (21) b (22) b (23) c (24) a (25) a (26) a (27) d (28) b (29) d (30) d (31) a (32) b (33) b (34) c (35) d (36) b (37) d (38) d (39) c (40) a (41) b (42) a (43) a (44) b (45) a (46) c (47) c (48) b (49) a (50) c (51) a (52) a (53) d (54) c (55) c (56) iv (57) d (58) a (59) d (60) b (61) b (62) d (63) c (64) d (65) b (66) a (67) d (68) a (69) d (70) c (71) d (72) a (73) c (74) d (75) b (76) a (77)

Notes on OperatingSystem Chapter 1 – Introduction to OS

What is an Operating System?

§       Operating System is a Resource Manager.–      Handles multiple computer resources: CPU, Internal/External memory, Processes, Tasks,

Applications, Users, etc…–      Manages and allocates resources to multiple users or multiple jobs running at the same time

(e.g., processor time, memory space, I/O devices)–      Arranges to use the computer hardware in an efficient manner (maximize throughput, minimize

response time) and in a fair manner.

§       It is a Control Program.–      Manages all the components of a complex computer system in an integrated manner.  –      Controls the execution of user programs and I/O devices to prevent errors and improper use of the

computer resources. –      Looks over and protects the computer.

§       It is an extended/virtual machine-      An interface between the user and hardware that hides the details of the hardware (e.g., I/O).-      Constructs higher-level (virtual) resources out of lower-level (physical) resources (e.g., files).-      Definition: Is a collection of software enhancements, executed on the bare hardware, culminating

in a high-level virtual machine that serves as an advanced programming environment

Why Operating System?

§       Computer hardware is developed to execute user programs and make solving user problems easier.

§       An operating system makes a computer more convenient to use.-      It acts as an interface between user and computer hardware. Therefore, the end-users

are not particularly concerned with the computer’s architecture, and they view the computer system in terms of an application.

-      To programmers, it provides some basic utilities to assist him in creating programs, the management of files, and the control of I/O devices.

Operating System Objectives

§       Convenience-      Makes the computer more convenient to use

§       Efficiency-      Allows computer system resources to be used in an efficient manner

§       Ability to evolve-      Permit effective development, testing, and introduction of new system functions without

interfering with service

Services Provided by Operating Systems

§       Facilities for program creation-      Editors, compilers, linkers, debuggers, etc.

§       Program execution-      Loading in memory, I/O and file initialization.

§       Access to I/O and files-      Deals with the specifics of I/O and file formats.

§       System access-      Resolves conflicts for resource contention.-      Protection in access to resources and data.

§       Error detection and response-      internal and external hardware errors

§       memory error§       device failure

-      software errors§       arithmetic overflow§       access forbidden memory locations

-      operating system cannot grant request of application

§       Accounting-      collect statistics-      monitor performance-      used to anticipate future enhancements-      used for billing users

Computer System Components

§       A computer system can be divided in to four components.

-      The Hardware: Provides basic computing resources (CPU, memory, I/O devices).

-      The Operating System: Controls and coordinates the use of the hardware among the various application programs for the various users.

-      The Application Programs: Define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs).

-      The Users: Users (people, machines, other computers).§       These components can be viewed as layers, where each layer uses the services provided by the layer beneath it.

What is a computer Network?

A network is any collection of independent computers that communicate with one another over a shared network medium.A computer network is a collection of two or more connected computers. When these computers are joined in a network, people can share files and peripherals such as modems, printers, tape backup drives, or CD-ROM drives. When networks at multiple locations are connected using services available from phone companies, people can send e-mail, share links to the global Internet, or conduct video conferences in real time with other remote users. As companies rely on applications like electronic mail and database management for core business operations, computer networking becomes increasingly more important.

Every network includes:

* At least two computers Server or Client workstation.* Networking Interface Card's (NIC)* A connection medium, usually a wire or cable, although wireless communication between networked computers and peripherals is also possible.* Network Operating system software, such as Microsoft Windows NT or 2000, Novell NetWare, Unix and Linux.

Types of Networks:LANs (Local Area Networks)

A network is any collection of independent computers that communicate with one another over a shared network medium. LANs are networks usually confined to a geographic area, such as a single building or a college campus. LANs can be small, linking as few as three computers, but often link hundreds of computers used by thousands of people. The development of standard networking protocols and media has resulted in worldwide proliferation of LANs throughout business and educational organizations.WANs (Wide Area Networks)

Wide area networking combines multiple LANs that are geographically separate. This is accomplished by connecting the different LANs using services such as dedicated leased phone lines, dial-up phone lines (both synchronous and asynchronous), satellite links, and data packet carrier services. Wide area networking can be as simple as a modem and remote access server for employees to dial into, or it can be as complex as hundreds of branch offices globally linked using special routing protocols and filters to minimize the expense of sending data sent over vast distances.Internet

The Internet is a system of linked networks that are worldwide in scope and facilitate data communication services such as remote login, file transfer, electronic mail, the World Wide Web and newsgroups.

With the meteoric rise in demand for connectivity, the Internet has become a communications highway for millions of users. The Internet was initially restricted to military and academic institutions, but now it is a full-fledged conduit for any and all forms of information and commerce. Internet websites now provide personal, educational, political and economic resources to every corner of the planet.Intranet

With the advancements made in browser-based software for the Internet, many private organizations are implementing intranets. An intranet is a private network utilizing Internet-type tools, but available only within that organization. For large organizations, an intranet provides an easy access mode to corporate information for employees.MANs (Metropolitan area Networks)

The refers to a network of computers with in a City.VPN (Virtual Private Network)

VPN uses a technique known as tunneling to transfer data securely on the Internet to a remote access server on your workplace network. Using a VPN helps you save money by using the public Internet instead of making long–distance phone calls to connect securely with your private network. There are two ways to create a VPN connection, by dialing an Internet service provider (ISP), or connecting directly to Internet.Categories of Network:Peer to Peer and Server/Client NetworkNetwork can be divided in to two main categories:

* Peer-to-peer.* Server – based.

In peer-to-peer networking there are no dedicated servers or hierarchy among the computers. All of the computers are equal and therefore known as peers. Normally each computer serves as Client/Server and there is no one assigned to be an administrator responsible for the entire network.

Peer-to-peer networks are good choices for needs of small organizations where the users are allocated in the same general area, security is not an issue and the organization and the network will have limited growth within the foreseeable future.

The term Client/server refers to the concept of sharing the work involved in processing data between the client computer and the most powerful server computer.The client/server network is the most efficient way to provide:

* Databases and management of applications such as Spreadsheets, Accounting, Communications and Document management.* Network management.* Centralized file storage.

The client/server model is basically an implementation of distributed or cooperative processing. At the heart of the model is the concept of splitting application functions between a client and a server processor. The division of labor between the different processors enables the application designer to place an application function on the processor that is most appropriate for that function. This lets the software designer optimize the use of processors--providing the greatest possible return on investment for the hardware.

Client/server application design also lets the application provider mask the actual location of application function. The user often does not know where a specific operation is executing. The entire function may execute in either the PC or server, or the function may be split between them. This masking of application function locations enables system implementers to upgrade portions of a system over time with a minimum disruption of application operations, while protecting the investment in

existing hardware and software.OSI ModelThe OSI Model:

Open System Interconnection (OSI) reference model has become an International standard and serves as a guide for networking. This model is the best known and most widely used guide to describe networking environments. Vendors design network products based on the specifications of the OSI model. It provides a description of how network hardware and software work together in a layered fashion to make communications possible. It also helps with trouble shooting by providing a frame of reference that describes how components are supposed to function.

There are seven to get familiar with and these are the physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and the application layer.

* Physical Layer, is just that the physical parts of the network such as wires, cables, and there media along with the length. Also this layer takes note of the electrical signals that transmit data throughout system.* Data Link Layer, this layer is where we actually assign meaning to the electrical signals in the network. The layer also determines the size and format of data sent to printers, and other devices. Also I don't want to forget that these are also called nodes in the network. Another thing to consider in this layer is will also allow and define the error detection and correction schemes that insure data was sent and received.* Network Layer, this layer provides the definition for the connection of two dissimilar networks.* Transport Layer, this layer allows data to be broken into smaller packages for data to be distributed and addressed to other nodes (workstations).* Session Layer, this layer helps out with the task to carry information from one node (workstation) to another node (workstation). A session has to be made before we can transport information to another computer.* Presentation Layer, this layer is responsible to code and decode data sent to the node.* Application Layer, this layer allows you to use an application that will communicate with say the operation system of a server. A good example would be using your web browser to interact with the operating system on a server such as Windows NT, which in turn gets the data you requested.

Network Architectures:Ethernet Network ArchitectureEthernet

Ethernet is the most popular physical layer LAN technology in use today. Other LAN types include Token Ring, Fast Ethernet, Fiber Distributed Data Interface (FDDI), Asynchronous Transfer Mode (ATM) and LocalTalk. Ethernet is popular because it strikes a good balance between speed, cost and ease of installation. These benefits, combined with wide acceptance in the computer marketplace and the ability to support virtually all popular network protocols, make Ethernet an ideal networking technology for most computer users today. The Institute for Electrical and Electronic Engineers (IEEE) defines the Ethernet standard as IEEE Standard 802.3. This standard defines rules for configuring an Ethernet network as well as specifying how elements in an Ethernet network interact with one another. By adhering to the IEEE standard, network equipment and network protocols can communicate efficiently.Fast Ethernet

For Ethernet networks that need higher transmission speeds, the Fast Ethernet standard (IEEE 802.3u) has been established. This standard raises the Ethernet speed limit from 10 Megabits per second (Mbps)

to 100 Mbps with only minimal changes to the existing cable structure. There are three types of Fast Ethernet: 100BASE-TX for use with level 5 UTP cable, 100BASE-FX for use with fiber-optic cable, and 100BASE-T4 which utilizes an extra two wires for use with level 3 UTP cable. The 100BASE-TX standard has become the most popular due to its close compatibility with the 10BASE-T Ethernet standard. For the network manager, the incorporation of Fast Ethernet into an existing configuration presents a host of decisions. Managers must determine the number of users in each site on the network that need the higher throughput, decide which segments of the backbone need to be reconfigured specifically for 100BASE-T and then choose the necessary hardware to connect the 100BASE-T segments with existing 10BASE-T segments. Gigabit Ethernet is a future technology that promises a migration path beyond Fast Ethernet so the next generation of networks will support even higher data transfer speeds.Token Ring ArchitectureToken Ring

Token Ring is another form of network configuration which differs from Ethernet in that all messages are transferred in a unidirectional manner along the ring at all times. Data is transmitted in tokens, which are passed along the ring and viewed by each device. When a device sees a message addressed to it, that device copies the message and then marks that message as being read. As the message makes its way along the ring, it eventually gets back to the sender who now notes that the message was received by the intended device. The sender can then remove the message and free that token for use by others.

Various PC vendors have been proponents of Token Ring networks at different times and thus these types of networks have been implemented in many organizations.FDDI architectureFDDI

FDDI (Fiber-Distributed Data Interface) is a standard for data transmission on fiber optic lines in a local area network that can extend in range up to 200 km (124 miles). The FDDI protocol is based on the token ring protocol. In addition to being large geographically, an FDDI local area network can support thousands of users.Protocols:

Network protocols are standards that allow computers to communicate. A protocol defines how computers identify one another on a network, the form that the data should take in transit, and how this information is processed once it reaches its final destination. Protocols also define procedures for handling lost or damaged transmissions or "packets." TCP/IP (for UNIX, Windows NT, Windows 95 and other platforms), IPX (for Novell NetWare), DECnet (for networking Digital Equipment Corp. computers), AppleTalk (for Macintosh computers), and NetBIOS/NetBEUI (for LAN Manager and Windows NT networks) are the main types of network protocols in use today.

Although each network protocol is different, they all share the same physical cabling. This common method of accessing the physical network allows multiple protocols to peacefully coexist over the network media, and allows the builder of a network to use common hardware for a variety of protocols. This concept is known as "protocol independence,"

Some Important Protocols and their job:Protocol Acronym Its JobPoint-To-Point TCP/IP The backbone protocol of the internet. Popular also for intranets using the internetTransmission Control Protocol/internet Protocol TCP/IP The backbone protocol of the internet. Popular also for intranets using the internet

Internetwork Package Exchange/Sequenced Packet Exchange IPX/SPX This is a standard protocol for Novell Network Operating SystemNetBIOS Extended User Interface NetBEUI This is a Microsoft protocol that doesn't support routing to other networksFile Transfer Protocol FTP Used to send and receive files from a remote hostHyper Text Transfer Protocol HTTP Used for the web to send documents that are encoded in HTML.Network File Services NFS Allows network nodes or workstations to access files and drives as if they were their own.Simple Mail Transfer Protocol SMTP Used to send Email over a networkTelnet Used to connect to a host and emulate a terminal that the remote server can recognizeIntroduction to TCP/IP Networks:

TCP/IP-based networks play an increasingly important role in computer networks. Perhaps one reason for their appeal is that they are based on an open specification that is not controlled by any vendor.What Is TCP/IP?

TCP stands for Transmission Control Protocol and IP stands for Internet Protocol. The term TCP/IP is not limited just to these two protocols, however. Frequently, the term TCP/IP is used to refer to a group of protocols related to the TCP and IP protocols such as the User Datagram Protocol (UDP), File Transfer Protocol (FTP), Terminal Emulation Protocol (TELNET), and so on.The Origins of TCP/IP

In the late 1960s, DARPA (the Defense Advanced Research Project Agency), in the United States, noticed that there was a rapid proliferation of computers in military communications. Computers, because they can be easily programmed, provide flexibility in achieving network functions that is not available with other types of communications equipment. The computers then used in military communications were manufactured by different vendors and were designed to interoperate with computers from that vendor only. Vendors used proprietary protocols in their communications equipment. The military had a multi vendor network but no common protocol to support the heterogeneous equipment from different vendorsNet work Cables and Stuff:

In the network you will commonly find three types of cables used these are the, coaxial cable, fiber optic and twisted pair.Thick Coaxial Cable

This type cable is usually yellow in color and used in what is called thicknets, and has two conductors. This coax can be used in 500-meter lengths. The cable itself is made up of a solid center wire with a braided metal shield and plastic sheathing protecting the rest of the wire.Thin Coaxial Cable

As with the thick coaxial cable is used in thicknets the thin version is used in thinnets. This type cable is also used called or referred to as RG-58. The cable is really just a cheaper version of the thick cable.Fiber Optic Cable

As we all know fiber optics are pretty darn cool and not cheap. This cable is smaller and can carry a vast amount of information fast and over long distances.Twisted Pair Cables

These come in two flavors of unshielded and shielded.Unshielded Twisted Pair and Shielded Twisted PairShielded Twisted Pair (STP)

Is more common in high-speed networks. The biggest difference you will see in the UTP and STP is that the STP use's metallic shield wrapping to protect the wire from interference.

-Something else to note about these cables is that they are defined in numbers also. The bigger the number the better the protection from interference. Most networks should go with no less than a CAT 3 and CAT 5 is most recommended.

-Now you know about cables we need to know about connectors. This is pretty important and you will most likely need the RJ-45 connector. This is the cousin of the phone jack connector and looks real similar with the exception that the RJ-45 is bigger. Most commonly your connector are in two flavors and this is BNC (Bayonet Naur Connector) used in thicknets and the RJ-45 used in smaller networks using UTP/STP.Unshielded Twisted Pair (UTP)

This is the most popular form of cables in the network and the cheapest form that you can go with. The UTP has four pairs of wires and all inside plastic sheathing. The biggest reason that we call it Twisted Pair is to protect the wires from interference from themselves. Each wire is only protected with a thin plastic sheath.Ethernet Cabling

Now to familiarize you with more on the Ethernet and it's cabling we need to look at the 10's. 10Base2, is considered the thin Ethernet, thinnet, and thinwire which uses light coaxial cable to create a 10 Mbps network. The cable segments in this network can't be over 185 meters in length. These cables connect with the BNC connector. Also as a note these unused connection must have a terminator, which will be a 50-ohm terminator.

10Base5, this is considered a thicknet and is used with coaxial cable arrangement such as the BNC connector. The good side to the coaxial cable is the high-speed transfer and cable segments can be up to 500 meters between nodes/workstations. You will typically see the same speed as the 10Base2 but larger cable lengths for more versatility.

10BaseT, the “T” stands for twisted as in UTP (Unshielded Twisted Pair) and uses this for 10Mbps of transfer. The down side to this is you can only have cable lengths of 100 meters between nodes/workstations. The good side to this network is they are easy to set up and cheap! This is why they are so common an ideal for small offices or homes.

100BaseT, is considered Fast Ethernet uses STP (Shielded Twisted Pair) reaching data transfer of 100Mbps. This system is a little more expensive but still remains popular as the 10BaseT and cheaper than most other type networks. This on of course would be the cheap fast version.

10BaseF, this little guy has the advantage of fiber optics and the F stands for just that. This arrangement is a little more complicated and uses special connectors and NIC's along with hubs to create its network. Pretty darn neat and not to cheap on the wallet.

An important part of designing and installing an Ethernet is selecting the appropriate Ethernet medium.

There are four major types of media in use today: Thickwire for 10BASE5 networks, thin coax for 10BASE2 networks, unshielded twisted pair (UTP) for 10BASE-T networks and fiber optic for 10BASE-FL or Fiber-Optic Inter-Repeater Link (FOIRL) networks. This wide variety of media reflects the evolution of Ethernet and also points to the technology's flexibility. Thickwire was one of the first cabling systems used in Ethernet but was expensive and difficult to use. This evolved to thin coax, which is easier to work with and less expensive.Network Topologies:What is a Network topology?

A network topology is the geometric arrangement of nodes and cable links in a LAN,

There are three topology's to think about when you get into networks. These are the star, rind, and the bus.

Star, in a star topology each node has a dedicated set of wires connecting it to a central network hub. Since all traffic passes through the hub, the hub becomes a central point for isolating network problems and gathering network statistics.

Ring, a ring topology features a logically closed loop. Data packets travel in a single direction around the ring from one network device to the next. Each network device acts as a repeater, meaning it regenerates the signal

Bus, the bus topology, each node (computer, server, peripheral etc.) attaches directly to a common cable. This topology most often serves as the backbone for a network. In some instances, such as in classrooms or labs, a bus will connect small workgroupsCollisions:

Ethernet is a shared media, so there are rules for sending packets of data to avoid conflicts and protect data integrity. Nodes determine when the network is available for sending packets. It is possible that two nodes at different locations attempt to send data at the same time. When both PCs are transferring a packet to the network at the same time, a collision will result.

Minimizing collisions is a crucial element in the design and operation of networks. Increased collisions are often the result of too many users on the network, which results in a lot of contention for network bandwidth. This can slow the performance of the network from the user's point of view. Segmenting the network, where a network is divided into different pieces joined together logically with a bridge or switch, is one way of reducing an overcrowded network.Ethernet Products:

The standards and technology that have just been discussed help define the specific products that network managers use to build Ethernet networks. The following text discusses the key products needed to build an Ethernet LAN.Transceivers

Transceivers are used to connect nodes to the various Ethernet media. Most computers and network interface cards contain a built-in 10BASE-T or 10BASE2 transceiver, allowing them to be connected directly to Ethernet without requiring an external transceiver. Many Ethernet devices provide an AUI connector to allow the user to connect to any media type via an external transceiver. The AUI connector consists of a 15-pin D-shell type connector, female on the computer side, male on the transceiver side.

Thickwire (10BASE5) cables also use transceivers to allow connections.

For Fast Ethernet networks, a new interface called the MII (Media Independent Interface) was developed to offer a flexible way to support 100 Mbps connections. The MII is a popular way to connect 100BASE-FX links to copper-based Fast Ethernet devices.Network Interface CardsNetwork Interface Cards:

Network interface cards, commonly referred to as NICs, and are used to connect a PC to a network. The NIC provides a physical connection between the networking cable and the computer's internal bus. Different computers have different bus architectures; PCI bus master slots are most commonly found on 486/Pentium PCs and ISA expansion slots are commonly found on 386 and older PCs. NICs come in three basic varieties: 8-bit, 16-bit, and 32-bit. The larger the number of bits that can be transferred to the NIC, the faster the NIC can transfer data to the network cable.

Many NIC adapters comply with Plug-n-Play specifications. On these systems, NICs are automatically configured without user intervention, while on non-Plug-n-Play systems, configuration is done manually through a setup program and/or DIP switches.

Cards are available to support almost all networking standards, including the latest Fast Ethernet environment. Fast Ethernet NICs are often 10/100 capable, and will automatically set to the appropriate speed. Full duplex networking is another option, where a dedicated connection to a switch allows a NIC to operate at twice the speed.Hubs/Repeaters:

Hubs/repeaters are used to connect together two or more Ethernet segments of any media type. In larger designs, signal quality begins to deteriorate as segments exceed their maximum length. Hubs provide the signal amplification required to allow a segment to be extended a greater distance. A hub takes any incoming signal and repeats it out all ports.

Ethernet hubs are necessary in star topologies such as 10BASE-T. A multi-port twisted pair hub allows several point-to-point segments to be joined into one network. One end of the point-to-point link is attached to the hub and the other is attached to the computer. If the hub is attached to a backbone, then all computers at the end of the twisted pair segments can communicate with all the hosts on the backbone. The number and type of hubs in any one-collision domain is limited by the Ethernet rules. These repeater rules are discussed in more detail later.Network Type Max NodesPer Segment Max DistancePer Segment10BASE-T10BASE210BASE510BASE-FL 2301002 100m185m500m2000mAdding Speed:

While repeaters allow LANs to extend beyond normal distance limitations, they still limit the number of nodes that can be supported. Bridges and switches, however, allow LANs to grow significantly larger by virtue of their ability to support full Ethernet segments on each port. Additionally, bridges and switches selectively filter network traffic to only those packets needed on each segment - this significantly increases throughput on each segment and on the overall network. By providing better performance and more flexibility for network topologies, bridges and switches will continue to gain popularity among network managers.Bridges:

The function of a bridge is to connect separate networks together. Bridges connect different networks types (such as Ethernet and Fast Ethernet) or networks of the same type. Bridges map the Ethernet addresses of the nodes residing on each network segment and allow only necessary traffic to pass through the bridge. When a packet is received by the bridge, the bridge determines the destination and source segments. If the segments are the same, the packet is dropped ("filtered"); if the segments are different, then the packet is "forwarded" to the correct segment. Additionally, bridges do not forward bad or misaligned packets.

Bridges are also called "store-and-forward" devices because they look at the whole Ethernet packet before making filtering or forwarding decisions. Filtering packets, and regenerating forwarded packets enable bridging technology to split a network into separate collision domains. This allows for greater distances and more repeaters to be used in the total network design.Ethernet SwitchesEthernet Switches:

Ethernet switches are an expansion of the concept in Ethernet bridging. LAN switches can link four, six, ten or more networks together, and have two basic architectures: cut-through and store-and-forward. In the past, cut-through switches were faster because they examined the packet destination address only before forwarding it on to its destination segment. A store-and-forward switch, on the other hand, accepts and analyzes the entire packet before forwarding it to its destination.

It takes more time to examine the entire packet, but it allows the switch to catch certain packet errors and keep them from propagating through the network. Both cut-through and store-and-forward switches separate a network into collision domains, allowing network design rules to be extended. Each of the segments attached to an Ethernet switch has a full 10 Mbps of bandwidth shared by fewer users, which results in better performance (as opposed to hubs that only allow bandwidth sharing from a single Ethernet). Newer switches today offer high-speed links, FDDI, Fast Ethernet or ATM. These are used to link switches together or give added bandwidth to high-traffic servers. A network composed of a number of switches linked together via uplinks is termed a "collapsed backbone" network.Routers:

Routers filter out network traffic by specific protocol rather than by packet address. Routers also divide networks logically instead of physically. An IP router can divide a network into various subnets so that only traffic destined for particular IP addresses can pass between segments. Network speed often decreases due to this type of intelligent forwarding. Such filtering takes more time than that exercised in a switch or bridge, which only looks at the Ethernet address. However, in more complex networks, overall efficiency is improved by using routers.What is a network firewall?

A firewall is a system or group of systems that enforces an access control policy between two networks. The actual means by which this is accomplished varies widely, but in principle, the firewall can be thought of as a pair of mechanisms: one which exists to block traffic, and the other which exists to permit traffic. Some firewalls place a greater emphasis on blocking traffic, while others emphasize permitting traffic. Probably the most important thing to recognize about a firewall is that it implements an access control policy. If you don't have a good idea of what kind of access you want to allow or to deny, a firewall really won't help you. It's also important to recognize that the firewall's configuration, because it is a mechanism for enforcing policy, imposes its policy on everything behind it. Administrators for firewalls managing the connectivity for a large number of hosts therefore have a heavy responsibility.Network Design Criteria:

Ethernets and Fast Ethernets have design rules that must be followed in order to function correctly. Maximum number of nodes, number of repeaters and maximum segment distances are defined by the electrical and mechanical design properties of each type of Ethernet and Fast Ethernet media.

A network using repeaters, for instance, functions with the timing constraints of Ethernet. Although electrical signals on the Ethernet media travel near the speed of light, it still takes a finite time for the signal to travel from one end of a large Ethernet to another. The Ethernet standard assumes it will take roughly 50 microseconds for a signal to reach its destination.

Ethernet is subject to the "5-4-3" rule of repeater placement: the network can only have five segments connected; it can only use four repeaters; and of the five segments, only three can have users attached to them; the other two must be inter-repeater links.

If the design of the network violates these repeater and placement rules, then timing guidelines will not be met and the sending station will resend that packet. This can lead to lost packets and excessive resent packets, which can slow network performance and create trouble for applications. Fast Ethernet has modified repeater rules, since the minimum packet size takes less time to transmit than regular Ethernet. The length of the network links allows for a fewer number of repeaters. In Fast Ethernet networks, there are two classes of repeaters. Class I repeaters have a latency of 0.7 microseconds or less and are limited to one repeater per network. Class II repeaters have a latency of 0.46 microseconds or less and are limited to two repeaters per network. The following are the distance (diameter) characteristics for these types of Fast Ethernet repeater combinations:Fast Ethernet Copper FiberNo RepeatersOne Class I RepeaterOne Class II RepeaterTwo Class II Repeaters 100m200m200m205m 412m*272m272m228m* Full Duplex Mode 2 km

When conditions require greater distances or an increase in the number of nodes/repeaters, then a bridge, router or switch can be used to connect multiple networks together. These devices join two or more separate networks, allowing network design criteria to be restored. Switches allow network designers to build large networks that function well. The reduction in costs of bridges and switches reduces the impact of repeater rules on network design.

Each network connected via one of these devices is referred to as a separate collision domain in the overall network.Types of Servers:Device Servers

A device server is defined as a specialized, network-based hardware device designed to perform a single or specialized set of server functions. It is characterized by a minimal operating architecture that requires no per seat network operating system license, and client access that is independent of any operating system or proprietary protocol. In addition the device server is a "closed box," delivering extreme ease of installation, minimal maintenance, and can be managed by the client remotely via a Web browser.

Print servers, terminal servers, remote access servers and network time servers are examples of device servers which are specialized for particular functions. Each of these types of servers has unique configuration attributes in hardware or software that help them to perform best in their particular arena.Print Servers

Print servers allow printers to be shared by other users on the network. Supporting either parallel and/or serial interfaces, a print server accepts print jobs from any person on the network using supported protocols and manages those jobs on each appropriate printer.

Print servers generally do not contain a large amount of memory; printers simply store information in a queue. When the desired printer becomes available, they allow the host to transmit the data to the appropriate printer port on the server. The print server can then simply queue and print each job in the order in which print requests are received, regardless of protocol used or the size of the job.Multiport Device Servers

Devices that are attached to a network through a multiport device server can be shared between terminals and hosts at both the local site and throughout the network. A single terminal may be connected to several hosts at the same time (in multiple concurrent sessions), and can switch between them. Multiport device servers are also used to network devices that have only serial outputs. A connection between serial ports on different servers is opened, allowing data to move between the two devices.

Given its natural translation ability, a multi-protocol multiport device server can perform conversions between the protocols it knows, like LAT and TCP/IP. While server bandwidth is not adequate for large file transfers, it can easily handle host-to-host inquiry/response applications, electronic mailbox checking, etc. And it is far more economical than the alternatives of acquiring expensive host software and special-purpose converters. Multiport device and print servers give their users greater flexibility in configuring and managing their networks.

Whether it is moving printers and other peripherals from one network to another, expanding the dimensions of interoperability or preparing for growth, multiport device servers can fulfill your needs,

all without major rewiring.Access Servers

While Ethernet is limited to a geographic area, remote users such as traveling sales people need access to network-based resources. Remote LAN access, or remote access, is a popular way to provide this connectivity. Access servers use telephone services to link a user or office with an office network. Dial-up remote access solutions such as ISDN or asynchronous dial introduce more flexibility. Dial-up remote access offers both the remote office and the remote user the economy and flexibility of "pay as you go" telephone services. ISDN is a special telephone service that offers three channels, two 64 Kbps "B" channels for user data and a "D" channel for setting up the connection. With ISDN, the B channels can be combined for double bandwidth or separated for different applications or users. With asynchronous remote access, regular telephone lines are combined with modems and remote access servers to allow users and networks to dial anywhere in the world and have data access. Remote access servers provide connection points for both dial-in and dial-out applications on the network to which they are attached. These hybrid devices route and filter protocols and offer other services such as modem pooling and terminal/printer services. For the remote PC user, one can connect from any available telephone jack (RJ45), including those in a hotel rooms or on most airplanes.Network Time Servers

A network time server is a server specialized in the handling of timing information from sources such as satellites or radio broadcasts and is capable of providing this timing data to its attached network. Specialized protocols such as NTP or udp/time allow a time server to communicate to other network nodes ensuring that activities that must be coordinated according to their time of execution are synchronized correctly. GPS satellites are one source of information that can allow global installations to achieve constant timing.IP Addressing:

An IP (Internet Protocol) address is a unique identifier for a node or host connection on an IP network. An IP address is a 32 bit binary number usually represented as 4 decimal values, each representing 8 bits, in the range 0 to 255 (known as octets) separated by decimal points. This is known as "dotted decimal" notation.

Example: 140.179.220.200

It is sometimes useful to view the values in their binary form.

140 .179 .220 .200

10001100.10110011.11011100.11001000

Every IP address consists of two parts, one identifying the network and one identifying the node. The Class of the address and the subnet mask determine which part belongs to the network address and which part belongs to the node address.Address Classes:

There are 5 different address classes. You can determine which class any IP address is in by examining the first 4 bits of the IP address.

Class A addresses begin with 0xxx, or 1 to 126 decimal.

Class B addresses begin with 10xx, or 128 to 191 decimal.

Class C addresses begin with 110x, or 192 to 223 decimal.

Class D addresses begin with 1110, or 224 to 239 decimal.

Class E addresses begin with 1111, or 240 to 254 decimal.

Addresses beginning with 01111111, or 127 decimal, are reserved for loopback and for internal testing on a local machine. [You can test this: you should always be able to ping 127.0.0.1, which points to yourself] Class D addresses are reserved for multicasting. Class E addresses are reserved for future use. They should not be used for host addresses.

Now we can see how the Class determines, by default, which part of the IP address belongs to the network (N) and which part belongs to the node (n).

Class A -- NNNNNNNN.nnnnnnnn.nnnnnnn.nnnnnnn

Class B -- NNNNNNNN.NNNNNNNN.nnnnnnnn.nnnnnnnn

Class C -- NNNNNNNN.NNNNNNNN.NNNNNNNN.nnnnnnnn

In the example, 140.179.220.200 is a Class B address so by default the Network part of the address (also known as the Network Address) is defined by the first two octets (140.179.x.x) and the node part is defined by the last 2 octets (x.x.220.200).

In order to specify the network address for a given IP address, the node section is set to all "0"s. In our example, 140.179.0.0 specifies the network address for 140.179.220.200. When the node section is set to all "1"s, it specifies a broadcast that is sent to all hosts on the network. 140.179.255.255 specifies the example broadcast address. Note that this is true regardless of the length of the node section.Private Subnets:

There are three IP network addresses reserved for private networks. The addresses are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. They can be used by anyone setting up internal IP networks, such as a lab or home LAN behind a NAT or proxy server or a router. It is always safe to use these because routers on the Internet will never forward packets coming from these addresses

Subnetting an IP Network can be done for a variety of reasons, including organization, use of different physical media (such as Ethernet, FDDI, WAN, etc.), preservation of address space, and security. The most common reason is to control network traffic. In an Ethernet network, all nodes on a segment see all the packets transmitted by all the other nodes on that segment. Performance can be adversely affected under heavy traffic loads, due to collisions and the resulting retransmissions. A router is used to connect IP networks to minimize the amount of traffic each segment must receive.Subnet Masking

Applying a subnet mask to an IP address allows you to identify the network and node parts of the address. The network bits are represented by the 1s in the mask, and the node bits are represented by the 0s. Performing a bitwise logical AND operation between the IP address and the subnet mask results

in the Network Address or Number.

For example, using our test IP address and the default Class B subnet mask, we get:

10001100.10110011.11110000.11001000 140.179.240.200 Class B IP Address

11111111.11111111.00000000.00000000 255.255.000.000 Default Class B Subnet Mask

10001100.10110011.00000000.00000000 140.179.000.000 Network AddressDefault subnet masks:

Class A - 255.0.0.0 - 11111111.00000000.00000000.00000000

Class B - 255.255.0.0 - 11111111.11111111.00000000.00000000

Class C - 255.255.255.0 - 11111111.11111111.11111111.00000000

CIDR -- Classless InterDomain Routing.

CIDR was invented several years ago to keep the internet from running out of IP addresses. The "classful" system of allocating IP addresses can be very wasteful; anyone who could reasonably show a need for more that 254 host addresses was given a Class B address block of 65533 host addresses. Even more wasteful were companies and organizations that were allocated Class A address blocks, which contain over 16 Million host addresses! Only a tiny percentage of the allocated Class A and Class B address space has ever been actually assigned to a host computer on the Internet.

People realized that addresses could be conserved if the class system was eliminated. By accurately allocating only the amount of address space that was actually needed, the address space crisis could be avoided for many years. This was first proposed in 1992 as a scheme called Supernetting.

The use of a CIDR notated address is the same as for a Classful address. Classful addresses can easily be written in CIDR notation (Class A = /8, Class B = /16, and Class C = /24)

It is currently almost impossible for an individual or company to be allocated their own IP address blocks. You will simply be told to get them from your ISP. The reason for this is the ever-growing size of the internet routing table. Just 5 years ago, there were less than 5000 network routes in the entire Internet. Today, there are over 90,000. Using CIDR, the biggest ISPs are allocated large chunks of address space (usually with a subnet mask of /19 or even smaller); the ISP's customers (often other, smaller ISPs) are then allocated networks from the big ISP's pool. That way, all the big ISP's customers (and their customers, and so on) are accessible via 1 network route on the Internet.

It is expected that CIDR will keep the Internet happily in IP addresses for the next few years at least. After that, IPv6, with 128 bit addresses, will be needed. Under IPv6, even sloppy address allocation would comfortably allow a billion unique IP addresses for every person on earthExamining your network with commands:

Ping

PING is used to check for a response from another computer on the network. It can tell you a great deal

of information about the status of the network and the computers you are communicating with.

Ping returns different responses depending on the computer in question. The responses are similar depending on the options used.

Ping uses IP to request a response from the host. It does not use TCP

.It takes its name from a submarine sonar search - you send a short sound burst and listen for an echo - a ping - coming back.

In an IP network, `ping' sends a short data burst - a single packet - and listens for a single packet in reply. Since this tests the most basic function of an IP network (delivery of single packet), it's easy to see how you can learn a lot from some `pings'.

To stop ping, type control-c. This terminates the program and prints out a nice summary of the number of packets transmitted, the number received, and the percentage of packets lost, plus the minimum, average, and maximum round-trip times of the packets.

Sample ping session

PING localhost (127.0.0.1): 56 data bytes64 bytes from 127.0.0.1: icmp_seq=0 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=1 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=2 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=3 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=4 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=5 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=6 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=7 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=8 ttl=255 time=2 ms64 bytes from 127.0.0.1: icmp_seq=9 ttl=255 time=2 ms

localhost ping statistics

10 packets transmitted, 10 packets received, 0% packet lossround-trip min/avg/max = 2/2/2 msmeikro$

The Time To Live (TTL) field can be interesting. The main purpose of this is so that a packet doesn't live forever on the network and will eventually die when it is deemed "lost." But for us, it provides additional information. We can use the TTL to determine approximately how many router hops the packet has gone through. In this case it's 255 minus N hops, where N is the TTL of the returning Echo Replies. If the TTL field varies in successive pings, it could indicate that the successive reply packets are going via different routes, which isn't a great thing.

The time field is an indication of the round-trip time to get a packet to the remote host. The reply is measured in milliseconds. In general, it's best if round-trip times are under 200 milliseconds. The time it takes a packet to reach its destination is called latency. If you see a large variance in the round-trip times (which is called "jitter"), you are going to see poor performance talking to the host

NSLOOKUP

NSLOOKUP is an application that facilitates looking up hostnames on the network. It can reveal the IP address of a host or, using the IP address, return the host name.

It is very important when troubleshooting problems on a network that you can verify the components of the networking process. Nslookup allows this by revealing details within the infrastructure.NETSTAT

NETSTAT is used to look up the various active connections within a computer. It is helpful to understand what computers or networks you are connected to. This allows you to further investigate problems. One host may be responding well but another may be less responsive.IPconfig

This is a Microsoft windows NT, 2000 command. It is very useful in determining what could be wrong with a network.

This command when used with the /all switch, reveal enormous amounts of troubleshooting information within the system.

Windows 2000 IP Configuration

Host Name . . . . . . . . . . . . : cowderPrimary DNS Suffix . . . . . . . :Node Type . . . . . . . . . . . . : BroadcastIP Routing Enabled. . . . . . . . : NoWINS Proxy Enabled. . . . . . . . : NoWINS Proxy Enabled. . . . . . . . : NoConnection-specific DNS Suffix . :Description . . . . . . . . . . . :WAN (PPP/SLIP) InterfacePhysical Address. . . . . . . . . : 00-53-45-00-00-00DHCP Enabled. . . . . . . . . . . : NoIP Address. . . . . . . . . . . . : 12.90.108.123Subnet Mask . . . . . . . . . . . : 255.255.255.255Default Gateway . . . . . . . . . : 12.90.108.125DNS Servers . . . . . . . . . . . : 12.102.244.2204.127.129.2Traceroute

Traceroute on Unix and Linux (or tracert in the Microsoft world) attempts to trace the current network path to a destination. Here is an example of a traceroute run to www.berkeley.edu:

$ traceroute www.berkeley.edu

traceroute to amber.Berkeley.EDU (128.32.25.12), 30 hops max, 40 byte packets

1 sf1-e3.wired.net (206.221.193.1) 3.135 ms 3.021 ms 3.616 ms

2 sf0-e2s2.wired.net (205.227.206.33) 1.829 ms 3.886 ms 2.772 ms

3 paloalto-cr10.bbnplanet.net (131.119.26.105) 5.327 ms 4.597 ms 5.729 ms

4 paloalto-br1.bbnplanet.net (131.119.0.193) 4.842 ms 4.615 ms 3.425 ms

5 sl-sj-2.sprintlink.net (4.0.1.66) 7.488 ms 38.804 ms 7.708 ms

6 144.232.8.81 (144.232.8.81) 6.560 ms 6.631 ms 6.565 ms

7 144.232.4.97 (144.232.4.97) 7.638 ms 7.948 ms 8.129 ms

8 144.228.146.50 (144.228.146.50) 9.504 ms 12.684 ms 16.648 ms

9 f5-0.inr-666-eva.berkeley.edu (198.128.16.21) 9.762 ms 10.611 ms 10.403 ms

10 f0-0.inr-107-eva.Berkeley.EDU (128.32.2.1) 11.478 ms 10.868 ms 9.367 ms

11 f8-0.inr-100-eva.Berkeley.EDU (128.32.235.100) 10.738 ms 11.693 ms 12.520 ms

Network Protocols The Defense Advance Research Projects Agency (DARPA) originally developed Transmission Control Protocol/Internet Protocol (TCP/IP) to interconnect various defense department computer networks. The Internet, an international Wide Area Network, uses TCP/IP to connect government and educational institutions across the world. TCP/IP is also in widespread use on commercial and private networks. The TCP/IP suite includes the following protocols

Data Link LayerARP/RARP Address Resolution Protocol/Reverse AddressDCAP Data Link Switching Client Access Protocol

Network LayerDHCP Dynamic Host Configuration ProtocolDVMRP Distance Vector Multicast Routing ProtocolICMP/ICMPv6 Internet Control Message ProtocolIGMP Internet Group Management ProtocolIP Internet Protocol version 4IPv6 Internet Protocol version 6MARS Multicast Address Resolution ServerPIM Protocol Independent Multicast-Sparse Mode (PIM-SM)RIP2 Routing Information ProtocolRIPng for IPv6 Routing Information Protocol for IPv6RSVP Resource ReSerVation setup ProtocolVRRP Virtual Router Redundancy Protocol

Transport LayerISTP

Mobile IP Mobile IP ProtocolRUDP Reliable UDPTALI Transport Adapter Layer InterfaceTCP Transmission Control ProtocolUDP User Datagram ProtocolVan Jacobson compressed TCPXOT X.25 over TCP

Session LayerBGMP Border Gateway Multicast ProtocolDiameter DIS Distributed Interactive SimulationDNS Domain Name ServiceISAKMP/IKE Internet Security Association and Key Management Protocol and Internet Key Exchange ProtocoliSCSI Small Computer Systems InterfaceLDAP Lightweight Directory Access ProtocolMZAP Multicast-Scope Zone Announcement ProtocolNetBIOS/IP NetBIOS/IP for TCP/IP Environment

Application LayerCOPS Common Open Policy ServiceFANP Flow Attribute Notification ProtocolFinger User Information ProtocolFTP File Transfer ProtocolHTTP Hypertext Transfer ProtocolIMAP4 Internet Message Access Protocol rev 4IMPPpre/IMPPmes Instant Messaging and Presence ProtocolsIPDC IP Device ControlIRC ·Internet Relay Chat ProtocolISAKMP Internet Message Access Protocol version 4rev1ISP NTP Network Time ProtocolPOP3 Post Office Protocol version 3Radius Remote Authentication Dial In User ServiceRLOGIN Remote LoginRTSP Real-time Streaming ProtocolSCTP Stream Control Transmision ProtocolS-HTTP Secure Hypertext Transfer ProtocolSLP Service Location ProtocolSMTP Simple Mail Transfer ProtocolSNMP Simple Network Management ProtocolSOCKS Socket Secure (Server)TACACS+ Terminal Access Controller Access Control SystemTELNET TCP/IP Terminal Emulation ProtocolTFTP Trivial File Transfer ProtocolWCCP Web Cache Coordination ProtocolX-Window X Window

RoutingBGP-4 Border Gateway ProtocolEGP Exterior Gateway ProtocolEIGRP Enhanced Interior Gateway Routing ProtocolHSRP Cisco Hot Standby Router ProtocolIGRP Interior Gateway RoutingNARP NBMA Address Resolution ProtocolNHRP Next Hop Resolution ProtocolOSPF Open Shortest Path FirstTRIP Telephony Routing over IP

TunnelingATMP Ascend Tunnel Management ProtocolL2F The Layer 2 Forwarding ProtocolL2TP Layer 2 Tunneling ProtocolPPTP Point to Point Tunneling Protocol

SecurityAH Authentication HeaderESP Encapsulating Security PayloadTLS Transport Layer Security Protocol

The TCP/IP suite is illustrated here in relation to the OSI model:Click the protocols on the map to see more details.

TCP / IP Suite

IP

The Internet Protocol (IP), defined by IETF RFC791, is the routing layer datagram service of the TCP/IP suite. All other protocols within the TCP/IP suite, except ARP and RARP, use IP to route frames from host to host. The IP frame header contains routing information and control information associated with datagram delivery.

The IP header structure is as follows:4

8

16

32 bitsVer.

IHL

Type of serviceTotal lengthIdentification

FlagsFragment offsetTime to liveProtocol Header checksumSource addressDestination addressOption + PaddingDataIP header structure

VersionVersion field indicates the format of the Internet header.

IHLInternet header length is the length of the Internet header in 32-bit words. Points to the beginning of the data. The minimum value for a correct header is 5.

Type of serviceIndicates the quality of service desired. Networks may offer service precedence, meaning that they accept traffic only above a certain precedence at times of high load. There is a three-way trade-off between low delay, high reliability and high throughput.Bits 0-2: Precedence111 Network control.110 Internetwork control.101 CRITIC/ECP.100 Flash override.011 Flash.010 Immediate.001 Priority.000 Routine.

Bit 3: Delay0 Normal delay.1 Low delay.

Bit 4: Throughput0 Normal throughput.1 High throughput.

Bit 5: Reliability0 Normal reliability.1 High reliability.

Bits 6-7: Reserved for future use.

Total lengthLength of the datagram measured in bytes, including the Internet header and data. This field allows the length of a datagram to be up to 65,535 bytes, although such long datagrams are impractical for most hosts and networks. All hosts must be prepared to accept datagrams of up to 576 bytes, regardless of whether they arrive whole or in fragments. It is recommended that hosts send datagrams larger than 576 bytes only if the destination is prepared to accept the larger datagrams.

IdentificationIdentifying value assigned by the sender to aid in assembling the fragments of a datagram.

Flags3 bits. Control flags:

Bit 0 is reserved and must be zero

Bit 1: Don’t fragment bit:0 May fragment.1 Don’t fragment.

Bit 2: More fragments bit:0 Last fragment.1 More fragments.

Fragment offset13 bits. Indicates where this fragment belongs in the datagram. The fragment offset is measured in units of 8 bytes (64 bits). The first fragment has offset zero.

Time to liveIndicates the maximum time the datagram is allowed to remain in the Internet system. If this field contains the value zero, the datagram must be destroyed. This field is modified in Internet header processing. The time is measured in units of seconds. However, since every module that processes a datagram must decrease the TTL by at least one (even if it processes the datagram in less than 1 second), the TTL must be thought of only as an upper limit on the time a datagram may exist. The intention is to cause undeliverable datagrams to be discarded and to bound the maximum datagram lifetime.

ProtocolIndicates the next level protocol used in the data portion of the Internet datagram.

Header checksumA checksum on the header only. Since some header fields change, e.g., Time To Live, this is recomputed and verified at each point that the Internet header is processed.

Source address / destination address32 bits each. A distinction is made between names, addresses and routes. A name indicates an object to be sought. An address indicates the location of the object. A route indicates how to arrive at the object.

The Internet protocol deals primarily with addresses. It is the task of higher level protocols (such as host-to-host or application) to make the mapping from names to addresses. The Internet module maps Internet addresses to local net addresses. It is the task of lower level procedures (such as local net or gateways) to make the mapping from local net addresses to routes.

OptionsOptions may or may not appear in datagrams. They must be implemented by all IP modules (host and gateways). What is optional is their transmission in any particular datagram, not their implementation. In some environments, the security option may be required in all datagrams.

The option field is variable in length. There may be zero or more options. There are two possible formats for an option:

* A single octet of option type.* An option type octet, an option length octet and the actual option data octets.

The length octet includes the option type octet and the actual option data octets.

The option type octet has 3 fields:

1 bit: Copied flag. Indicates that this option is copied into all fragments during fragmentation:0 Copied.1 Not copied.

2 bits: Option class0 Control.1 Reserved for future use.2 Debugging and measurement.3 Reserved for future use.

5 bits: Option number.

DataIP data or higher layer protocol header.Enlarge

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IPv6

IP version 6 (IPv6) is a new version of the Internet Protocol based on IPv4. IPv4 and IPv6 are demultiplexed at the media layer. For example, IPv6 packets are carried over Ethernet with the content type 86DD (hexadecimal) instead of IPv4’s 0800.

IPv6 increases the IP address size from 32 bits to 128 bits, to support more levels of addressing hierarchy, a much greater number of addressable nodes and simpler auto-configuration of addresses. Scalability of multicast addresses is introduced. A new type of address called an anycast address is also defined, to send a packet to any one of a group of nodes.

Improved support for extensions and options - IPv6 options are placed in separate headers that are located between the IPv6 header and the transport layer header. Changes in the way IP header options are encoded allow more efficient forwarding, less stringent limits on the length of options, and greater flexibility for introducing new options in the future. The extension headers are: Hop-by-Hop Option, Routing (Type 0), Fragment, Destination Option, Authentication, Encapsulation Payload.

Flow labeling capability - A new capability has been added to enable the labeling of packets belonging to particular traffic flows for which the sender requests special handling, such as non-default Quality of Service or real-time service.

The IPv6 header structure is as follows:4

4

16

24

32 bitsVer.

Priority

Flow labelPayload length

Next header

Hop limit

Source address(128 Bits)

Destination address(128 bits)IPv6 header structure

VersionInternet Protocol Version number (IPv6 is 6).

PriorityEnables a source to identify the desired delivery priority of the packets. Priority values are divided into

ranges: traffic where the source provides congestion control and non-congestion control traffic.

Flow labelUsed by a source to label those products for which it requests special handling by the IPv6 router. The flow is uniquely identified by the combination of a source address and a non-zero flow label.

Payload lengthLength of payload (in octets).

Next headerIdentifies the type of header immediately following the IPv6 header.

Hop limit8-bit integer that is decremented by one by each node that forwards the packet. The packet is discarded if the Hop Limit is decremented to zero.

Source address128-bit address of the originator of the packet.

Destination address128-bit address of the intended recipient of the packet.Enlarge

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TCP

RFC793 http://www.cis.ohio-state.edu/htbin/rfc/rfc793.htmlRFC1146 http://www.cis.ohio-state.edu/htbin/rfc/rfc1146.htmlRFC1072 http://www.cis.ohio-state.edu/htbin/rfc/rfc1072.htmlThis RFC has been replaced by RFC 1323.The information on this page will be updated to suit the new RFC in the near future.RFC1693 http://www.cis.ohio-state.edu/htbin/rfc/rfc1693.html

IETF RFC793 defines the Transmission Control Protocol (TCP). TCP provides a reliable stream delivery and virtual connection service to applications through the use of sequenced acknowledgment with retransmission of packets when necessary.

The TCP header structure is as follows:16

32 bitsSource portDestination portSequence number

Acknowledgement numberOffset

Resrvd

U

A

P

R

S

F

WindowChecksum

Urgent pointerOption + PaddingDataTCP header structure

Source portSource port number.

Destination portDestination port number.

Sequence numberThe sequence number of the first data octet in this segment (except when SYN is present). If SYN is present, the sequence number is the initial sequence number (ISN) and the first data octet is ISN+1.

Acknowledgment numberIf the ACK control bit is set, this field contains the value of the next sequence number which the sender of the segment is expecting to receive. Once a connection is established, this value is always sent.

Data offset4 bits. The number of 32-bit words in the TCP header, which indicates where the data begins. The TCP header (even one including options) has a length which is an integral number of 32 bits.

Reserved6 bits. Reserved for future use. Must be zero.

Control bits6 bits. The control bits may be (from right to left):U (URG) Urgent pointer field significant.

A (ACK) Acknowledgment field significant.P (PSH) Push function.R (RST) Reset the connection.S (SYN) Synchronize sequence numbers.F (FIN) No more data from sender.

Window16 bits. The number of data octets which the sender of this segment is willing to accept, beginning with the octet indicated in the acknowledgment field.

Checksum16 bits. The checksum field is the 16 bit one’s complement of the one’s complement sum of all 16-bit words in the header and text. If a segment contains an odd number of header and text octets to be checksummed, the last octet is padded on the right with zeros to form a 16-bit word for checksum purposes. The pad is not transmitted as part of the segment. While computing the checksum, the checksum field itself is replaced with zeros.

Urgent Pointer16 bits. This field communicates the current value of the urgent pointer as a positive offset from the sequence number in this segment. The urgent pointer points to the sequence number of the octet following the urgent data. This field can only be interpreted in segments for which the URG control bit has been set.

OptionsOptions may be transmitted at the end of the TCP header and always have a length which is a multiple of 8 bits. All options are included in the checksum. An option may begin on any octet boundary.There are two possible formats for an option:

*A single octet of option type.*An octet of option type, an octet of option length, and the actual option data octets.

The option length includes the option type and option length, as well as the option data octets.

The list of options may be shorter than that designated by the data offset field because the contents of the header beyond the End-of-Option option must be header padding i.e., zero.

A TCP must implement all options.

DataTCP data or higher layer protocol.Enlarge

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UDP

The User Datagram Protocol (UDP), defined by IETF RFC768, provides a simple, but unreliable message service for transaction-oriented services. Each UDP header carries both a source port identifier and destination port identifier, allowing high-level protocols to target specific applications and services among hosts.

The UDP header structure is shown as follows:16

32 bitsSource port

Destination portLength

Checksum

DataUDP header structure

Source portSource port is an optional field. When used, it indicates the port of the sending process and may be assumed to be the port to which a reply should be addressed in the absence of any other information. If not used, a value of zero is inserted.

Destination portDestination port has a meaning within the context of a particular Internet destination address.

LengthThe length in octets of this user datagram, including this header and the data. The minimum value of the length is eight.

ChecksumThe 16-bit one’s complement of the one’s complement sum of a pseudo header of information from the IP header, the UDP header and the data, padded with zero octets at the end (if necessary) to make a multiple of two octets.ARP/RARP

RFC826 http://www.cis.ohio-state.edu/htbin/rfc/rfc826.htmlRFC1293 http://www.cis.ohio-state.edu/htbin/rfc/rfc1293.htmlThis RFC has been replaced by RFC 2390.The information on this page will be updated to suit the new RFC in the near future.RFC1390 http://www.cis.ohio-state.edu/htbin/rfc/rfc1390.html

TCP/IP uses the Address Resolution Protocol (ARP) and the Reverse Address Resolution Protocol (RARP) to initialize the use of Internet addressing on an Ethernet or other network that uses its own

media access control (MAC). ARP allows a host to communicate with other hosts when only the Internet address of its neighbors is known. Before using IP, the host sends a broadcast ARP request containing the Internet address of the desired destination system.

The ARP/RARP header structure is shown in the illustration below.16

32 bitsHardware Type

Protocol TypeHLen (8)

Plen (8)

OperationSender Hardware AddressSender Protocol AddressTarget Hardware AddressTarget Protocol AddressARP/RARP header structure

Hardware typeSpecifies a hardware interface type for which the sender requires a response.

Protocol typeSpecifies the type of high-level protocol address the sender has supplied.

HLenHardware address length.

PLenProtocol address length.

OperationThe values are as follows:1 ARP request.2 ARP response.3 RARP request.4 RARP response.5 Dynamic RARP request.6 Dynamic RARP reply.7 Dynamic RARP error.8 InARP request.9 InARP reply.

Sender hardware addressHLen bytes in length.

Sender protocol addressPLen bytes in length.

Target hardware addressHLen bytes in length.

Target protocol addressPLen bytes in length.Enlarge

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DCAP

http://info.internet.isi.edu/in-notes/rfc/files/rfc2114.txt .

The (DLSw) Data Link Switching Client Access Protocol is used between workstations and routers to transport SNA/NetBIOS traffic over TCP sessions.

Since the Data Link Switching Protocol, RFC 1795, was published, some software vendors have begun implementing DLSw on workstations. The implementation of DLSw on a large number of workstations raises the important issues of scalability and efficiency. Since DLSw is a switch-to-switch protocol, it is not efficient when implemented on workstations. DCAP addresses these issues. It introduces a hierarchical structure to resolve the scalability problems. All workstations are clients to the router (server) rather than peers to the router. This creates a client/server model. It also provides a more efficient protocol between the workstation (client) and the router (server).

(Application layer)

DCAP Packet Header

The DCAP packet header is used to identify the message type and length of the frame. This is a general purpose header used for each frame that is passed between the DCAP server and the clien8 16Protocol ID/Version Number Message TypePacket LengthDCAP Header Format

Protocol IDThe Protocol ID uses the first 4 bits of this field and is set to 1000.

Version numberThe Version number uses the next 4 bits in this field and is set to 0001.

Message type

The message type is the DCAP message type.

The following message types exist:

DCAP Frame Name

Code

Function CAN U REACH 0x01 Find if the station given is reachableI CAN REACH 0x02 Positive response to CAN U REACHI CANNOT REACH 0x03 Negative response to CAN U REACHSTART DL 0x04 Setup session for given addressesDL STARTED 0x05 Session startedSTART DL FAILED 0x06 Session Start failedXID FRAME 0x07 XID frameCONTACT STN 0x08 Contact destination to establish SABMESTN CONTACTED 0x09 Station contacted - SABME mode setDATA FRAME 0x0A Connectionless Data Frame for a linkINFO FRAME 0x0B Connection oriented I-FrameHALT DL 0x0C Halt Data Link sessionHALT DL NOACK 0x0D Halt Data Link session without ackDL HALTED 0x0E Session haltedFCM FRAME 0x0F Data Link Session Flow Control MessageDGRM FRAME 0x11 Connectionless Datagram Frame for circuitCAP XCHANGE 0x12 Capabilities Exchange MessageCLOSE PEER REQUEST 0x13 Disconnect Peer Connection RequestCLOSE PEER RESPONSE 0x14 Disconnect Peer Connection ResponsePEER TEST REQ 0x1D Peer keepalive test requestPEER TEST RSP 0x1E Peer keepalive response

Packet lengthThe total packet length is the length of the packet including the DCAP header, DCAP data and user data. The minimum size of the packet is 4, which is the length of the header.

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ATMP

RFC 2107 http://www.cis.ohio-state.edu/htbin/rfc/rfc2107.html

The Ascend Tunnel Management Protocol (ATMP) is a protocol currently being used in Ascend Communication products to allow dial-in client software to obtain virtual presence on a user's home network from remote locations. A user calls into a remote NAS but instead of using an address belonging to a network directly supported by the NAS, the client software uses an address belonging to

the user's "Home Network". This address can be either provided by the client software or assigned from a pool of addresses from the Home Network address space. In either case, this address belongs to the Home Network and therefore special routing considerations are required in order to route packets to and from these clients. A tunnel between the NAS and a special “Home Agent” (HA) located on the Home Network is used to carry data to and from the client.The format of the ATMP header is shown in the following illustration:Version

Message type

IdentifierATMP packet structure

VersionThe ATMP protocol version must be 1.

Message typeATMP defines a set of request and reply messages sent with UDP. There are 7 different ATMP message types represented by the following values.MessageType Type CodeRegistration RequestChallenge RequestChallenge ReplyRegistration ReplyDeregister RequestDeregister ReplyError Notification

1234567

IdentifierA 16 bit number used to match replies with requests. A new value should be provided in each new request. Retransmissions of the same request should use the same identifier.

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L2F

RFC 2341 http://www.cis.ohio-state.edu/htbin/rfc/rfc2341.html

The Layer 2 Forwarding protocol (L2F) permits the tunneling of the link layer of higher layer protocols. Using such tunnels it is possible to divorce the location of the initial dial-up server from the

location at which the dial-up protocol connection is terminated and access to the network provided.The format of the packet is shown in the following illustration:

13 16 24 32F K P S 0 0 0 0 0 0 0 0 C

Ver

Protocol

Sequence (opt)Multiplex ID

Client IDLength

Payload offsetPacket key (optional)PayloadChecksumL2F packet structure

VersionThe major version of the L2F software creating the packet.

ProtocolThe protocol field specifies the protocol carried within the L2F packet.

SequenceThe sequence number is present if the S bit in the L2F header is set to 1.

Multiplex IDThe packet multiplex ID identifies a particular connection within a tunnel.

Client IDThe client ID (CLID) assists endpoints in demultiplexing tunnels.

LengthThe length is the size in octets of the entire packet, including the header, all the fields and the payload.

Payload offsetThis field specifies the number of bytes past the L2F header at which the payload data is expected to start. This field is present if the F bit in the L2F header is set to 1.

Packet keyThe key field is present if the K bit is set in the L2F header. This is part of the authentication process.

ChecksumThe checksum of the packet. The checksum field is present if the C bit in the L2F header is set to 1.

Option Messages

When the link is initiated, the endpoints communicate to verify the presence of L2F on the remote end, and to permit any needed authentication. The protocol for such negotiation is always 1, indicating L2F management. The message itself is structured as a sequence of single octets indicating an option. When the protocol field of an L2F specifies L2F management, the body of the packet is encoded as zero or more options. An option is a single octet message type, followed by zero or more sub-options. Each sub-option is a single byte sub-option value, and followed by additional bytes as appropriate for the sub-option.Possible option messages are:Invalid Invalid message.L2F CONF Request configuration.L2F CONF NAME Name of peer sending L2F CONF.L2F CONF CHAL Random number peer challenges.L2F CONF CLID Assigned CLID for peer to use.L2F OPEN Accept configuration.L2F OPEN NAME Name received from client.L2F OPEN CHAL Challenge client received.L2F OPEN RESP Challenge response from client.L2F ACK LCP1 LCP CONFACK accepted from client.L2F ACK LCP2 LCP CONFACK sent to client.L2F OPEN TYPE Type of authentication used.L2F OPEN ID ID associated with authentication.L2F REQ LCP0 First LCP CONFREQ from client.L2F CLOSE Request disconnect.L2F CLOSE WHY Reason code for close.L2F CLOSE STR ASCII string description.L2F ECHO Verify presence of peer.L2F ECHO RESP Respond to L2F_ECHO.

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L2TPIETF draft

The L2TP Protocol is used for integrating multi-protocol dial-up services into existing Internet Service Providers Point of Presence (hereafter referred to as ISP and POP, respectively). This protocol may also be used to solve the "multilink hunt-group splitting" problem. Multilink PPP, often used to aggregate ISDN B channels, requires that all channels composing a multilink bundle be grouped at a single Network Access Server (NAS). Because L2TP makes a PPP session appear at a location other than the physical point at which the session was physically received, it can be used to make all channels appear at a single NAS, allowing for a multilink operation even when the physical calls are spread across distinct physical NASs.

The format of the L2TP packet is shown in the following illustration:8 16 32 bitsT L X X S X O P X X X X VER LengthTunnel ID SESSION IDNs NrAVP (bytes +)L2TP packet structure

TThe T bit indicates the type of message. It is set to 0 for data messages and 1 for control messages.

LWhen set, this indicates that the Length field is present, indicating the total length of the received packet. Must be set for control messages.

XThe X bits are reserved for future extensions. All reserved bits are set to 0 on outgoing messages and are ignored on incoming messages.

SIf the S bit is set, both the Nr and Ns fields are present. S must be set for control messages.

OWhen set, this field indicates that the Offset Size field is present in payload messages. This bit is set to 0 for control messages.

PIf the Priority (P) bit is 1, this data message receives preferential treatment in its local queuing and transmission. LCP echo requests used as a keepalive for the link, for instance, are generally sent with this bit set to 1. Without it, a temporary interval of local congestion could result in interference with keepalive messages and unnecessary loss of the link. This feature is only for use with data messages. The P bit has a value of 0 for all control messages.

VerThe value of the ver bit is always 002. This indicates a version 1 L2TP message.

LengthOverall length of the message, including header, message type AVP, plus any additional AVP's associated with a given control message type.

Tunnel IDIdentifies the tunnel to which a control message applies. If an Assigned Tunnel ID has not yet been received from the peer, Tunnel ID must be set to 0. Once an Assigned Tunnel ID is received, all further packets must be sent with Tunnel ID set to the indicated value.

Call IDIdentifies the user session within a tunnel to which a control message applies. If a control message does not apply to a single user session within the tunnel (for instance, a Stop-Control-Connection-Notification message), Call ID must be set to 0.

NrThe sequence number expected in the next control message to be receivec.

NsThe sequence number for this data or control message.

Data messages have two additional fields before the AVP as follows:Offset size (16 bits) Offset pad (16 bits)Additional fields in L2TP payload message

Offset sizeThis field specifies the number of bytes past the L2TP header at which the payload data is expected to start. It is recommended that data thus skipped be initialized to 0s. If the offset size is 0, or the O bit is not set, the first byte following the last byte of the L2TP header is the first byte of payload data.

AVPThe AVP (Attribute-Value Pair) is a uniform method used for encoding message types and bodies throughout L2TP. The format of the AVP is given below:

16

32 bitsM

H

O

O

O

O

Overall length

Vendor IDAttribute

ValueL2TP AVP structure

MThe first six bits are a bit mask, describing the general attributes of the AVP. The M bit, known as the mandatory bit, controls the behavior required of an implementation which receives an AVP which it does not recognize.

H

The hidden bit controls the hiding of the data in the value field of an AVP. This capability can be used to avoid the passing of sensitive data, such as user passwords, as cleartext in an AVP.

Overall lengthEncodes the number of octets (including the overall length field itself) contained in this AVP. It is 10 bits, permitting a maximum of 1024 bytes of data in a single AVP.

Vendor IDThe IANA assigned SMI Network Management Private Enterprise Codes value, encoded in network byte order.

AttributeThe actual attribute, a 16-bit value with a unique interpretation across all AVP's defined under a given Vendor ID.

ValueThe value field follows immediately after the Attribute field, and runs for the remaining octets indicated in the overall length (i.e., overall length minus six octets of header).Enlarge

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PPTP

PPTP (Point to Point Tunneling Protocol) allows PPP to be channeled through an IP network. It uses a client-server architecture to decouple functions which exist in current Network Access Servers and support Virtual Private Networks. It specifies a call-control and management protocol which allows the server to control access for dial-in circuit switched calls originating from a PSTN or ISDN, or to initiate outbound circuit switched connections. PPTP uses a GRE-like (Generic Routing Encapsulation) mechanism to provide a flow- and congestion-controlled encapsulated datagram service for carrying PPP packets.The format of the header is shown in the following illustration:16

32 bitsLength

PPTP message typeMagic cookieControl message type

Reserved 0PPTP header structure

LengthTotal length in octets of this PPTP message including the entire PPTP header.

PPTP message typeThe message type. Possible values are:1 Control message.2 Management message.

Magic cookieThe magic cookie is always sent as the constant 0x1A2B3C4D. Its basic purpose is to allow the receiver to ensure that it is properly synchronized with the TCP data stream.

Control Message TypeValues may be:1 Start-Control-Connection-Request.2 Start-Control-Connection-Reply.3 Stop-Control-Connection-Request.4 Stop-Control-Connection-Reply.5 Echo-Request.6 Echo-Reply.

Call Management7 Outgoing-Call-Request.8 Outgoing-Call-Reply.9 Incoming-Call-Request.10 Incoming-Call-Reply.11 Incoming-Call-Connected.12 Call-Clear-Request.13 Call-Disconnect-Notify.

Error Reporting14 WAN-Error-Notify.

PPP Session Control15 Set-Link-Info.

ReservedA reserved field, must be set to 0.

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DHCP

This RFC has been replaced by RFC 2131.The information on this page will be updated to suit the new RFC in the near future.

The Dynamic Host Configuration Protocol (DHCP) provides Internet hosts with configuration parameters. DHCP is an extension of BOOTP. DHCP consists of two components: a protocol for delivering host-specific configuration parameters from a DHCP server to a host and a mechanism for allocation of network addresses to hosts.(Compliant with IETF RFC1531.)

The format of the header is shown in the following illustration:8

16

24

32 bitsOp (1)

Htype (1)Hlen (1) Hops (1)Xid (4 bytes)Secs (2 bytes)

Flags (2 bytes)Ciaddr (4 bytes)Yiaddr (4 bytes)Siaddr (4 bytes)Giaddr (4 bytes)

Chaddr (16 bytes)DHCP header structure

OpThe message operation code. Messages can be either BOOTREQUEST or BOOTREPLY.

HtypeThe hardware address type.

HlenThe hardware address length.

XidThe transaction ID.

SecsThe seconds elapsed since the client began the address acquisition or renewal process.

FlagsThe flags.

CiaddrThe client IP address.

YiaddrThe "Your" (client) IP address.

SiaddrThe IP address of the next server to use in bootstrap.

GiaddrThe relay agent IP address used in booting via a relay agent.

ChaddrThe client hardware address.Enlarge

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DVMRP

Distance Vector Multicast Routing Protocol (DVMRP) is an Internet routing protocol that provides an efficient mechanism for connectionless datagram delivery to a group of hosts across an internetwork. It is a distributed protocol that dynamically generates IP multicast delivery trees using a technique called Reverse Path MulticastingDVMRP combines many of the features of RIP with the Truncated Reverse Path Broadcasting (TRPB) algorithm. DVMRP is developed based upon RIP because an implementation was available and distance vector algorithms are simple, as compared to link-state algorithms. In addition, to allow experiments to traverse networks that do not support multicasting, a mechanism called tunneling was developed.DVMRP differs from RIP in one very important way. RIP routes and forwards datagrams to a particular destination. The purpose of DVMRP is to keep track of the return paths to the source of multicast datagrams. To make the explanation of DVMRP more consistent with RIP, the term destination is used instead of the more proper term source, however, datagrams are not forwarded to these destinations, but rather, originate from them.DVMRP packets are encapsulated in IP datagrams, with an IP protocol number of 2 (IGMP). All fields are transmitted in Network Byte Order. DVMRP packets use a common protocol header that specifies the IGMP Packet Type as DVMRP. DVMRP protocol packets should be sent with the Precedence field in the IP header set to Internetwork Control (hexadecimal 0xc0 for the Type of Service Octet). The common protocol header is as shown in the following illustration:

8 16 24 32 bits

Type

Code

ChecksumReserved

Min version

Maj versionDVMRP structure

TypePacket type. 0x13 indicates a DVMRP packet.

CodeDetermines the type of DVMRP packet. Currently, there are codes for DVMRP protocol message types as well as protocol analysis and troubleshooting packets. The protocol message codes may be as follows:Probe Neighbor discovery.Report Route exchange.Prune Pruning multicast delivery trees.Graft Grafting multicast delivery trees.Graft ack Acknowledging graft messages.

Checksum16-bit one's complement of the one's complement sum of the DVMRP message. The checksum must be calculated upon transmission and must be validated on reception of a packet. The checksum of the DVMRP message should be calculated with the checksum field set to zero.

ReservedReserved for later use.

Min versionMinor version. Value must be 0xFF for this version of DVMRP.

Maj versionMajor version. Value must be 3 for this version of DVMRP.

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ICMP

IETF RFC792 defines the Internet Control Message Protocol (ICMP). ICMP messages generally

contain information about routing difficulties with IP datagrams or simple exchanges such as time-stamp or echo transactions.

The ICMP header structure is shown as follows:8

16

32 bitsType

Code

ChecksumIdentifier

Sequence numberAddress maskICMP header structure

Type Code Description0 Echo reply.3 Destination unreachable.3 0 Net unreachable.3 1 Host unreachable.3 2 Protocol unreachable.3 3 Port unreachable.3 4 Fragmentation needed and DF set.3 5 Source route failed.4 Source quench.5 Redirect.5 0 Redirect datagrams for the network.5 1 Redirect datagrams for the host.5 2 Redirect datagrams for the type of service and network.5 3 Redirect datagrams for the type of service and host.8 Echo.11 Time exceeded.11 0 Time to live exceeded in transit.11 1 Fragment reassemble time exceeded.12 Parameter problem.13 Timestamp.14 Timestamp reply.15 Information request.16 Information reply.

ChecksumThe 16-bit one’s complement of the one’s complement sum of the ICMP message starting with the ICMP Type. For computing the checksum, the checksum field should be zero.

IdentifierAn identifier to aid in matching requests/replies; may be zero.

Sequence numberSequence number to aid in matching requests/replies; may be zero.

Address maskA 32-bit mask.Enlarge

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ICMPv6

This RFC has been replaced by RFC 2463.The information on this page will be updated to suit the new RFC in the near future.

This RFC has been replaced by RFC 2461.The information on this page will be updated to suit the new RFC in the near future.

The Internet Control Message Protocol (ICMP) was revised during the definition of IPv6. In addition, the multicast control functions of the IPv4 Group Membership Protocol (IGMP) are now incorporated with the ICMPv6.

The structure of the ICMPv6 header is shown in the following illustration.8

16

32 bitsType

Code

ChecksumICMPv6 header structure

TypeThe type of the message. Messages can be error or informational messages. Error messages can be Destination unreachable, Packet too big, Time exceed, Parameter problem. The possible informational messages are, Echo Request, Echo Reply, Group Membership Query, Group Membership Report, Group Membership Reduction.

CodeFor each type of message several different codes are defined.An example of this is the Destination Unreachable message, where possible messages are: no route to destination, communication with destination administratively prohibited, not a neighbor, address unreachable, port unreachable. For further details, refer to the standard.

  Machine language is the only language that the computer can directly execute and is different for each type of

A.    hardware computer only

B.    supercomputer only

C.    computer

D.    none of the above

 The three categories of programming languages are : machine language, assembly language and

A.    structured programming language

B.    high-level languages

C.    subprograms

D.    none of the above

 A job is a unit of work to be processed by the………..

 A computer can only execute instructions that are in

A.    assembly language

B.    machine language

C.    job control program

D.    none of the above

 The job control program translates the job control commands written by a programmer into

A.    high-level language

B.    assembly language

C.    machine language

D.    none of the above

Application programs are the programs that meet

A.    machine language needs

B.    job control program needs

C.    user's needs

D.    none of the above

When computers were first developed, machine language was the only way they could

A.  be programmed      B.  not be programmed C.  both (A) and (B)     D.  none of the above

 Often assembly language instructions will execute faster than those written in

A. machine language   B.  high-level languageC.  Pascal                               D.  none of the above

 Pascal can be used to write a wide variety of programs, from those that are highly scientific to those that are strongly

A. business oriented     B.  general oriented C.  source oriented       D.  none of the above

In Pascal, there is no limit to the length of an identifier, but some compilers only recognize the ,

A.    four characters in the identifier

B.    three characters in the identifier

C.    eight characters in the identifier

D.    none of the above

The formulation of user-defined identifiers should allow the rules for

A. identifiers                          B.  operations

C. computer                         D. none of the above

 A storage location whose value can change during program execution is referred to as

A. integer                               B.  variable

C  zero integer                        D. none of the above

An integer is a signed or. unsigned

A. a few numbers       B.  only one number C.  whole number        D. : none of the above

Variable of data type Boolean can represent only one of the two values

A. zero and one                      B.  true or false

C. three or four                      D. none of the above

 The data type char contains all of the characters that can be represented by a given                                       

A. identifier          B.  program

C. computer system.    D. none of the above

 The variable of type char can contain only a single character

A. of all time                          B.  at a time

C.  at the beginning     D.  none of the above

A vertical arrangement of information on worksheet is termed as

A. row                                   B.   vertical row

C. column                              D.  none of the above

The information stored in a cell is termed as

A.    COMMAND

B.    CONTENTSC.    BOOTD.    none of the above

 A collection of on-line reference information used to perform program operations, this is termed as

A.      FORMULA

B.         FIELD

        C.    Help

        D.    none of the above

Macro substitution is a powerful programming technique used in

A.    files

B.    command files

C.    data bases

D.    none of the above

 A command file is a disk file that has a series of

A.    command in it

B.    databases

C.    computer programs

D.    none of the above

 A command file is actually a

A.    data base

B.    computer memory

C.    computer program

D.    micro substitution

To print formatted reports with dBASE n, we use its built-in

A.    any particular format

B.    report generator

C.    computer memory

D.    none of the above

 A computer's main memory is called

A.    database

B.    computer memory

C.    random access memory or RAM

D.    none of the above

 Data in RAM also have names which are stored in memory variables instead of

A.    memory

B.    databases

C.    computer memory

D.    none of the above

Memory variables are temporary storage places for pieces of

A.    information

B.    databases

C.    RAM

D.    none of the above

 The command is Append. Which is the correct definition in the following?

A.    Formats screen and printer displays

B.    Allows us to add new data to our data base

C.    A condition is not true

D.    none of the above

The command name is B. Which is the correct definition in the following? '

A.    Refers to all records in the database

B.    Creates or edits a command file

C.    signals drive B for storing data files 

D. none of the above

 The CHR function tells us the character that goes along

A. with computer memory B   with a number

C.    with a data base

D.    none of the above

  When we set alternate to TRANSFER, dBASE created a disk file called:

A.    ALTERNATE ON

B.    TRANSFER.TXT

C.    QUIT dBASE

D.    none of the above

  Computer can only perform

A.    several basic operations

B.    two basic operations

C.    three basic operations

D.    none of the above

Assembly languages also referred to as low level languages

B.    machine language

C.    high language program

D.    none of the above

Lotus is an exciting and impressive piece of

A.    data base

B.    hardware computer system

C.    software computer system

D.    none of the above

In supercomputer, a machine must be capable of performing at least

A.    10 million arithmetic operations per second

B.    20 million arithmetic operations per second

C.    40 million arithmetic operations per second

D.  80 million arithmetic operations per second

 Before you can start WordStar, you need to be n the directory that contains all of the WordStar programs. The name of this directory is:

 If the directory docs not list the drive letter where you need to keep the data disk blank, you must change it with the

A.  M option

B . N option

C.    L option

D.    none of the above

LOTUS is an exciting and impressive piece-of

A.    computer hardware

B.    computer software

C.    computer

D.    none of the above

 An address that does not change if you copy the formula from one cell to another. The term of this definition is

A.    ASCII

B.    ADDRESSS                                                       

C.    ABSOLUTE ADDRESS

D.    none of the above

 A particular type of data locate in a column is termed as

A.    ATTRIBUTE

B.    BYTE

C.    BOOT

D.    none of the above

Unique location on a spread sheet identified by the intersection" between one row and one column. The term of this definition is

A.    CELL POINTER

B.    CELL

C.    BYTE

D.    none of the above

 Listing of files on a particular disk is termed as

A.    DISK PREFIX

B.    CELL

C.    DIRECTORY

D.    none of the above

1.  The model which provides a concrete expression of these concepts by means of two fundamental ideas — logical records and links, is called a

A.    relationship model

B.    network model

C.        hicrachical modelD. none of the above

2.  The network model has been established by

A.    CODASYL committee

B.    IBM

C.        ECA

D.    none of the above

3.  A link may be defined as the representation of anA. objects                               B, programs

C.  association                        D. none of the above

4.  DML is intended provide operations which ope- rate upon data stored in the

A, file                                     B. record

C. database                              D. none of the above

5.  In the hierarchical model a hierarchical schema is defined by a tree whose nodes are

A. database                            B. logical record types

C. links                                  D. none of the above

6.  The set of all values in the relations represents the contents of the

A. database                            B. record file

C. table                                   D. none of the above

7.  In hierarchical data model, the database is represented by

A. a directed graph     B.  tree structuresC. relation                               D, none of the above

8.  A Database Management System (DBMS) is a software system capable of supporting and managing any number of independent

A. results                               B. relations

D   none of the above

9.  Support for data independence is arguably the most important feature of a

A   system                              B, database system

C. relation                               D. none of the above

10.  Distinct levels of data independence arcA. two                                    B. three

C. four                                    D, none of the above

11.  Database software may be divided into

A.    four distinct categories

B.     three distinct categories

C.     two distinct categories

D.    none of the above

12.  Any large software project may be divided into several

A. project phases        B.  sub projects

C   hardware                           D. none of the above

13.  Data modeling occupies an important position in the

A. database file                      B. database life cycle

C. relation                               D. none of the above

14.  The term "software engineering" implies the application of scientific knowledge and discipline to the construction of

A.    database record

B.    computer hardware system

C.    computer software system

D.    none of the above

15.  Program correctness has been a strong motivation for much of the work in software engineering and

A.    high-level language programming

B.    programming language design

C.    Pascal

D.    none of the above

Answers:  1 2 3 4 5 B A B B B 11B

12A

13B

14C

15B

6 7 8 9 10A B C s

 For the novice, there is a recommended

A.    learning sequence

B.    sub-sequence

C.    interesting way

D.    none of the above

 In fact, the more you use LOTUS 1-2-3, the more you think of new and

A.    interesting ways to use it

B.    different ways to use it

C.    more complicated ways to use it

D.    none of the above

 LOTUS 1-2-3 operates with IBM and compatible

A.    hardware requirements only

B.    software requirements only

C.    both A and B or personal computers

D.    none of the above

Work sheets have been used to organize

A.    financial information only

B.    business information only

C.    financial and business information for years

D.    none of the above

   With the advent of the microcomputer, worksheets became

A.    electronic

B.    more complex

C.    easy

D.    none of the above

 Before you ran the installation program, you created a directory for the

A. WordStar files       B. programs

C. hard disk                         D. none of the above

 In earlier versions of WordStar, the Edit Menu was referred to as the

A,  Old Menu                       B.  Main Menu

C   Menu                               D. none of the above

WordStar also allows us to save a marked block of text in

A. a new file                          B. an old file

C. a program                        D. none of the above

 WordStar provides us reading a block of text into

A. a document                      B.  a program

C. a new file                          D.   none of the above

To perform any WordStar block operations, you must first mark the block of text

A.    not to be used

B.    to be used

C.    of program to be used

D.    none of the above

 WordStar supports

A.    documents

B.    background printing

C.    without printing

D.    none of the above

 All the file names that you give any WordStar document must confirm to the DOS

A.    file naming conventions

B.    and programs

C.    and document

D.    none of the above

 We can send dBASE reports to word processing system for editing or

A.    inclusion in other documents

B.    printing

C.    programming

D. none of the above

 dBASE is a data base management system for

A.    supercomputer

B.    microcomputer

C.    minicomputer

D   none of the above

  In computer world, a database is like our shoebox file, with a

A.    very rigid structure

B.    simple structure

C.    program

D.    none of the above

 There is a very important difference between human database managers and

A. computer database management systems B   any management system

C.    structure database systems

D.    none of the above

The computer does not understand anything

about

A.    any information

B.    programming languages

C.    information base on its context

D.    none of die above

We structure our database rigidly so the

A.    computer does not mistake

B.    program can be formed

C.    database is properly occurred

D.    none of the above

 We can send dBASE reports to word processing systems for further editing or inclusion

A.    in other documents

B.    of programming

C.    any other information

D.    none of the above

 Lotus is an exciting and impressive piece of

A. hardware computer system

B.    software computer system

C.    database

D.    none of the above

 Beginning in Module-2, you encounter many LOTUS

A.    commands

B.    piece of computer software

C.    1-2-3 commands

D.    none of the above

  The current worksheet is entirely in the

A. computer

B.    main memory of the computer

C.    programming

D none of the above

The name of WordStar's directory isA. WS5                                   B. WS7

C. WS4                                   D. none of the above

If you use WordStar on a dual-floppy system and start WordStar with drive A as the default you will need to change the logged drive to B when

A.    you put the computer on

B.    you start the program

C.    you change the drive

D.    none of the above

WordStar displays an alphabetical listing of as many files on the logged disk or

A.    it has room for

B.    it has directory specification

C.    it has Opening Menu

D.    none of the above

 An entity type may contain the declaration of another entity type, and so on, in order to define

A.    Pascal's record file

B.    hierarchical structure

C.    database

D.    none of the above

  Important point concerning the hierarchical model is the physical implementation of the

A. system                              B. software system

C. evaluated trees       D. none of the above

  The data model proposed by E.F. Codd in 1970 is called the

A.    Codd Model

B.     relational data model

C.    network model

D.    none of the above

 The basic idea is to consider a database as a collection of time varying tables called

A. relations                           B.  network model

C. Pascal's structure    D. none of the above

 The relational algebra is a set of operators which can be used to define new relations from

A. the old ones                     B. existing ones

C. system                              D. none of the above

 Relational algebra can be used to express

A.    relations

B.    system

C.    queries and updates

D.    none of the above

  SQL is a relational language which has also been implemented in several

A. DBMSs                            B. ECA

C. QUEL                              D. none of the above

Relational algebra is one of the basic concepts for defining

A.    high-level language

B.    relational language

C.    machine language

D.    none of the above

SQL is neither a pure algebraic language nor a

A.    machine language

B.    assembly language

C.    predicative language

D.    none of the above

  Codd shows that relational algebra is equivalent to first order

A.    differential equation

B.    predicate calculus

C.    differential calculus

D.    none of the above

  In SQL the statement Expand Table can be used at any time

A. old relation                      B. given relation

C. combination                    D. none of the above

The tutorial is designed to quickly acquaint you with the basic knowledge of

A.    Computer

B.    WordStar

C.    Software programming

D.    none of the above

To start WordStar on a computer with two floppy disk drives, you need to place a copy of your DOS disk in drive A before

A.    you start programming

B.    you format the disk

C.    you turn the computer on

D.    none of the above

Before you can start WordStar, you need to be in the directory that contains all of the

A.    WordStar programs

B.    computer technology

C.    basic working of WordStar

D.    none of the above

 The original WordStar was the very first software program,

A.    mention program

B.    mention word processor

C.    mention computing

D.    none of the above

Before a program written in high language can be executed, it must be translated into

A.    block structural language

B.    machine language

C.    structural programming language 

D.    none of the above

 A loop is usually the easiest way to perform a repetition task such as printing a list of

A.    a few names

B.    several hundred names

C.    One name only

D.    none of the above

 The syntax of a language can be described using syntax diagrams, such as those for

A.    Pascal

B.    loop

C.    sequence

D.    none of the above

 A program that adds three numbers together and determines the average is a

A. loop                                   B.  term

C.  sequence                           D. none of the above

 Those languages which are strongly oriented toward the programmer rather than toward the computer, they are termed as

A.    machine language

B.    high-level language

C.    assembly language

D.    none of the above

 Pascal contains statements that allow the programmer to efficiently alter the flow of programexecution by using decision

A.    structure only

B.    loops only

C.    structures and loops

D.    none of the above

In block-structured language, programs are com- posed of subprograms or blocks, each designed to perform a

A.    decision structures

B.    loop

C.    specific task

D.    none of the above

The important feature of Pascal is that it is a general-purpose

A.    programming language

B.    high level language

C.    source program

D   none of the above

  Pascal programs are usually translated into machine language by a

A.    batch processing

B.    computer

C.    block

D.    none of the above

 There is no limit to the length of

A.    Pascal program                                                           

B.    structured programming language

C.    an identifier

D.    none of the above

  Assembly languages also referred to as

A.    high language program

B.    low-level languages

C.    machine language

 Peripheral devices consist of input devices, out- put devices and

A.    logical operation                                                

B.    secondary storage device

C.    arithmetic operation

D.    none of the above

 The primary storage unit temporarily stores data, programs, and

A.    physical components

B.    peripheral devices

C.    processing results

D.    none of the above

The central processing unit consists of the arithmetic/logic unit, which performs arithmetic and logical operations, and the control unit, which controls the operations

of,

A.    CPU

B.    ALU

C.    peripheral devices

D.    none of the above

The relational model whose guiding ideas were published in 1970 has dominated the area of

A.    software system

B.    hardware system

C.    database research and development

D.    none of the above

  A link is represented by a diagram, called a  A.         Bachman diagram   B. Pascal diagram C.          Theory diagram     D. none of die above

   A great advantage of Modula-2 over Ada is that it is a

A. greater language     B. small language C. Pascal language     D. none of die above

 Integrity constraints are predicates which must be true for data stored in the

A. system                              B. hardware system

C. database                          D. none of the above

  In a distributed DBMS one may add a third factor which is the transmission time in the

A. relation                             B. system

C. network                           D. none of die above

A transaction is the unit of concurrency and A. system            B. recovery control C. software system     D. none of the above

A DBMS allows data manipulation through primitive operations which can be grouped to form A. data transactions      B. software system

C. hardware system     D. none of the above

 The INSERTION clause specifies the storage method as either AUTOMATIC or

A. DBMS                              B. MANUAL

C. CODASYL                      D. None of the above

 The RETENTION clause specifies the degree of freedom available to the members of a

A. database                          B. system

C. link                                   D. none of the above

When items stored in primary storage need to be kept permanently, they can be transferred to secondary storage. Example of secondary storage media are

A.  magnetic disks and tape

B.    air

C.    water

D.    none of the above

 Programs are list of instructions that a computer can use to solve a problem. A program or series of programs is called

A.    hardware

B.    software

C.    language program

D.    none of the above

  Pascal provides standard fifes, named

A.    input and output     B.  input only

C. output only                        D. none of the above

An operating system contains  A. one type of .program

B.    several types of programs

C.    only two types of programs

D.    none of the above

 Computers can only perform

A.    two basic operations                                              

B.    three basic operations

C.    several basic operations

D.    none of the above

A data model may be defined as a pattern according to which data are

A. organized                         B.  weakly organized

 The term 'software engineering' implies the application of scientific knowledge and discipline to the construction of

A; systems                            B. hardware systems

C. software systems    D. none of the above

 In software system, the data must be shared among

A. a very few users     B.  many different usersC. two users                          D. none of the above

One of the most important techniques for dealing with complexity in software systems is the

A.    principle of abstraction

B.    principle of stepwise refinement

C.    maintainability of the systemD  none of the above

Concurrency control in database management systems, including

A.    database procedure

B.    transaction

C.    alternatives to locking

D.    none of the above

 The developments in software engineering have led to the emergence of a

A.    programming language

B.    new class of programming language

C.    new class of system

D.    none of the above

 Program correctness has been a strong motivation for much of the work in software engineering and

A.    hardware system

B.    assembly language

C.    programming language design

D.    none of the above

 Modula-2 is a language which is suitable both for the implementation of

A.    database system only

B.    application programs

C.    database management systems and applicationprograms

D.    none of the above

The logical database design is a

A. three stage process B. two-stage process . C. four stage process   D. none of the above

Arithmetic and logic operations are the only types of instructions that the

(A)    CPU is able to execute

(B)    ALU is able to execute

(C)    Hardware is able to execute

(D)    none of the above

The primary storage unit also referred to as

(A)     main memory, primary memory

(B)     internal storage

(C)     both (A) and (B) ,(D) none of the above

 In a national election, the records of all the votes cast for the office of President are data when these votes are tabulated and the final total is determined, the result is called

(A) Input                                (B) information

(C) ALU                                (D) none of the above

A given computer system can have

(A)    only one input devices

(B)    not more than two input devices

(C)    many different input devices

(D)    none of the above

 Output devices; allow the user to examine the computer's output. Displaying output on the screen gives the user the results in a convenient, readable form; this output is referred to as

(A) hard copy                        (B) soft copy

(C) input devices                    (D) none of the above

  As with input devices, a particular computer system can have

(A)    only one output device

(B)    only two output devices

(C)    many different output devices

(D)    none of the above

 Disk and tape drives are commonly used

(A)    hard copy

(B)    soft copy

(C)    secondary storage devices

(D)    none of the above

 A computer is a device for automatically carrying out a/an :

(A)    information

(B)    instructions

(C)    program of instructions

(D)    none of the above

 One of the more modern programming languages is called:

(A)    higher language

(B)    Pascal

(C)    Assembly language

(D)    None of the above

Hardware consists of the actual

(A)    components of the computer

(B)    components of the computer system

(C)    components of the software

(D)    none of the above

 The component of the computer system which perform processing functions is called the

(A)    control unit

(B)    main memory

(C)    central processing unit (CPU)

(D)    none of the above

The arithmetic unit (ALU) performs

(A)    mathematics computations

(B)    primary memory

(C)    CPU

(D)    none of the above

 Peripheral devices can be divided into

(A)    four general categories

(B)    three general categories

(C)    two general categories

(D)    none of the above

 Programs and data that are entered into a computer to be processed are called

(A)    output

(B)    input

(C)    both (A) and (B)

(D)    none of the above

 When data is processed, or converted to some meaningful form, this is called

(A) ALU                                (B) CPU

(C) information                      (D) none of the above

 In supercomputer, a machine must be capable of performing atleast

(A)  5 million arithmetic operations per second

(B)   10 million arithmetic operations per second(C) 20 million arithmetic operations per second

(D) none of the above

For most business applications, the extremely high-speed processing capabilities of a super-computer

(A) are. necessary                  (B) are not necessary

(C)   both (A) and (B)     (D) none of the above

 Minicomputers manufactured today are more powerful than

(A) supercomputer       (B) mainframes

(C) microcomputer      (D) none of the above

Which of the following computer is currently the smallest and least costly computer

(A) microcomputer       (B) supercomputer(C) mainframes                      (D) none of the above

 Some programs direct the computer in its own internal operations. These are called

(A)    software

(B)    system programs

(C)    application programs

(D)    none of the above

The communication between the CPU and external modules takes place via the

(A) address only

(B)    data buses only

(C)    address and data buses

(D)    none of the above

 The SET SELECTION clause indicates how to access to set

A. occurrence                       B. a system

C, a software                        D. none of the above

  Once complied by the DBMS, the database scheme will be used to create and to control

A. system                              B. data storage

C.  a link                               D. none of the above

The way, the occurrence of an owner is linked to the occurrence of its

A. relation                             B. system

C. members                          D. none of the above

 The SOCRATE/CLIODDL can be used to define

A. records and file      B. relation

C. schemes                            D. none of the above

 In SOCRATE/CLIODDL one must specify the maximum numbers of occurrences for each

A. link                                   B. entity type

C. scheme                             D. none of the above

  An entity defines a block structure similar to

A.    hierarchical structure

B.    Pascal's record constructor

C.    scheme

D.    none of the above

If the value of maxim for the computer system used is 2147403647. Then the range of allowable integers for this particular system is

A. 2147483647 through - 2147483647

B. - 2147483647 through 2147483647

C. 2147483647 through zero

D none of the above

The Computer can access data stored on a hard disk more quickly than that stored

A.    on a floppy disk

B.    program

C.    memory

D.    rtbne of the above

The arithmetic logic shift unit (ALSU) is a combination circuit that performs a number of arithmetic and logic arid

A.  memory unit

B.     shift micro operations

C.     control memory

D. none of the above

 The block diagram of the processor unit consists Of a file of 14 registers, on ALSU, and three buses that provide the data path

A.    within the system

B.    within the unit

C.    within the tile

D.    none of the above

The 14 registers in the processor .unit are assigned special (asks by the

A.    ALSU

B.    CPU

C   DOR

D  none of the above

 A computer usually have .several input, and output (I/O) devices, these collectively known as

A.    function unit

B.    bit-pattern

C.    peripherals

D.    none of the above

 In Pascal, it is impossible-for variable values oV. Constants to be used as

A   instructions

B.    bit pattern

C.    peripherals                                                                  

D.    none of the above     

 Irv-Pascal, in exponential notation, the number iswritten as a value which is multiplied by _10 to

A.  any power

B. the appropriate power

C.    10th power

D.    none of the above

 In characteristic, a plus sign (+) is to be shifted

A.    to the left a certain number of places

B.    to the zero a certain numbers of places

C.    to the right a certain number of places

D.    none of the above

In characteristic, a negative sign (-) indicates that the decimal point should be shifted a certain number of places

A.    to the right

B.    to the zero

C.    to the left

D. none of the above

 The standard identifiers are the words

A.    real only

B.    real, integer only

C.    real, integer, Boolean, and char

D.    none of the above

  User-defined identifiers are those identifiers that are supplied by the programmer to name objects or processes that are used

A.    within the database

B.     within the program

C.    within (lie Pascal compiler

D.    none of the above

 The primary storage unit in a Computer is divided into

A.    two separate storage locations only

B.    three separate storage locations only

C.    many separate storage locations only

D.    none of the above

  A variable has distinct characteristic

A.    a name, a type only

B.    a value,-a name only

C.    a name, a value, a type

D.    none of the .above

  A variable name may be any valid user-defined identifier and serve as a symbolic name for a

A.    database only

B.    language program

C.    specific location in memory

D.    none of the above

 In Pascal, a data type determines both the group of possible values of the variables and the allowable

A.    identifiers

B.    operations for the variable

C.    storage location

D.    none of the above

  DIR is used only after a read operation, to receive the data from

A- database

B.    data bus

C.    data-bus buffers

D.    none of the above

Eight processor Registers are used as for manipulating data through

A.    data bus ,

B.    database   

C.    program instructor

D.    none of the above

The program counter, can be changed by the programmer by means of

A. branch type instructions

B. ordinary instructions

C: programming language

D. none of the above     

The basic model -for a digital computer is stillknown  as the

A. Pascal machine

B.    Neumann machine

C.    Charles Babbage machine

D. none of the above

The structure, for A sample Digital Computerreferred to    

A. SDC                           

B. SDCc .

C. SDQcc

D. none Of trie above

The two main categories of software are application software and

A.    machine language

B.    system software

C.    high-level languages

D. none of the above

 Some digital computers are called decimal/ computers because

A.    decimal number can not be read in such computer

B.     decimal number can be read in such computer

C.     it does not contain decimal number

D.    none of the above

 Which computer is often found In small businesses and in homes and classrooms?

A.    mainframe

B.    supercomputer

C.    microcomputer

D. none of the above

 Which computer's primary storage unit is usually smaller than that of the other types of computer?

 A.  minicomputer

B.    microcomputer

C.    supercomputer

D.    none of the above                                                  

  A computer which uses a series of digits to represent all types of information is called

A.   a digital computer

B.     an analogue computer

C.    super computer

D.    none of the above

We can combine dBASE power with other software systems by transferring

A.    files to an fro dBASE

B.    program to another program

C.    files to an fro Database

D.    none of the above

 It is not possible to declare all the functions on an entity, or all of the subtypes, at the

A.    existing data

B.    entire database

C.  module creation

D. none of the above

  Integrity constraints are predicates which must be free for data stored in

A.    an entity

B.    the database

C.    the system

D.    none of the above

One of the aspects of data integrity is related to data access and

A.    on the database

B.    the language programming

C.    privacy problems

D.    none of the above

A DBMS allows data manipulation through primitive operations which can be grouped to form

A.    database transactions

B.    database modification

C.    software modules                                      D.    none of the above

The INGRES system is composed with

A.    one module

B.    two modules

C.    four modules

D.    none of the above

 QUEL is interpreted by the

A.    DBMS system

B.    INGRES system

C.    SQL system

D.    none of the above

It is also possible to access the relational DBMS through application program written in

A.    high-level programming language

B.    Pascal language programming

C.    procedural language

D.    none of the above

We can send dBASE reports to word processing systems for further editing or inclusion

A. in other programs

B. in other documents

C.    in other systems

D.    none of the above

 The top three lines in a LOTUS 1-2-3 is termed as

A.    PANEL

B.    CONTROL PANEL

C.    EXTENSION

D.    none of the above

The module scheme does not provide one of the common features of modules in programming, namely

A.    the accessing a number of shared modules

B.    the hiding of names

C.    and the partitioning of the same space

D.    both B and C

 Modules of the kind used in ADA and Module-2 allow one to declare a collection of procedures and functions that

A.   hiding the names

B.    reference each other

C.   partitioning of the same space

D.   none of the above

 The advantage of using storage system like binary relations or triples which does not keep all the function values on

A.    an entity together

B.    entire database

C existing data

D. none of the above

 SQL is a relational language which has also been implemented in several

A. DBMSs                             B. QUEL

C. INGRES                          D. none of the above

 Several relational languages have been defined for different

A.    relational DBMS ,

B.    relational DBMSs

C.    QUEL languages

D.    none of the above

Relational algebra is one of the basic concepts for defining

A.    programming languages

B.    relational languages

C.  high-level programming language D. none of the above

Using the operators of relational algebra one may manipulate and query the database in a

A.    non-homogeneous manner

B.    homogeneous manner

C.    both A and B

D.    none of the above

  Modula-2 is an ideal language for interacting with an existing DBMS, where a suitable module

A.    has not been provided

B.    has been provided

C.    both A and B

D.    none of the above

 Locking mechanism guarantees exclusive access to an item of data while a lock

A.    has not been used

B.    is in force ,

C.    both A and B

D.    none of the above

The ability to define such abstract objects, together with appropriate operations, is invaluable for

A.    programming language

B.    high-level programming language

C.    database applications

D.    none of the above

 One of the most important technique for dealing with complexity in software system is the principle of

A.    programming language

B.    abstraction

C.    database technology

D.    hone of the above

The term 'software engineering' implies the application of scientific knowledge to the construction of

A.    computer software systems

B.    computer hardware systems

C.    high-level programming language

D.    none of the above

 By error we mean any deviation from the behavior stipulated by the

A.    database system

B.    requirements analysis

C.    incorrect data modeling

D.    none of the above

  By implementation we mean the transformation of our design into a database system which operates on a particular machine, usually under the control of

A.    software system

B.    hardware system

D. none of the above

 Boolean variables are sometimes referred to as

A.    variables

B.    real variables

C.    logical variables

D.    none of the above

In Pascal, decimal notation, requires that a real number contains at least one digit before and after the

A.    exponential notation

B.    decimal point

C.    zero

D.    none of the above