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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
COMP 107 FUNDAMENTAL COMPUTER
PRINCIPLE &
PROGRAMMING Chapter II
ByD.Balaganesh
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Network
• Networkone computer connected to more then one computer is called Network
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Advantages of networking
• Connectivity and Communication• Data Sharing• Hardware Sharing• Internet Access• Internet Access Sharing• Data Security and Management• Performance Enhancement and Balancing• Entertainment04/11/2023 Balaganesh -Lincoln University 3
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Balaganesh -Lincoln University
Network• Network: A set of devices (nodes) connected by communication links• Node: Computer, printer, or any device capable of sending and/or
receiving data• To be considered effective and efficient, a network must meet a
number of criteria
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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Type of Connection
1-5
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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Type of Connection• Point-to-point
– Dedicated link between two devices– The entire capacity of the channel is reserved– Ex) Microwave link, TV remote control
• Multipoint – More than two devices share a single link– Capacity of the channel is either
• Spatially shared: Devices can use the link simultaneously• Timeshare: Users take turns
1-6
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Balaganesh -Lincoln University
Physical Topology
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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Mesh Topology• Dedicated point-to-point link to
every other nodes • A mesh network with n nodes
has n(n-1)/2 links. A node has n-1 I/O ports (links)
• Advantages: No traffic problems, robust, security, easy fault identification & isolation
• Disadvantages: Difficult installation/reconfiguration, space, cost
1-8
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
04/11/2023 Balaganesh -Lincoln University
Star Topology• Dedicated point-to-point link only to a central controller, called a hub • Hub acts as an exchange: No direct traffic between devices• Advantages: Less expensive, robust • Disadvantages: dependency of the whole on one single point, the hub
1-9
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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Bus Topology• One long cable that links all nodes • tap, drop line, cable end• limit on the # of devices, distance between nodes • Advantages: Easy installation, cheap • Disadvantages: Difficult reconfiguration, no fault isolation, a fault or
break in the bus stops all transmission
1-10
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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Ring Topology• Dedicated point-to-point link only with the two nodes on each sides • One direction, repeater • Advantages: Easy reconfiguration, fault isolation• Disadvantage: Unidirectional traffic, a break in the ring cab disable the
entire network
1-11
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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Hybrid Topology• Example: Main star topology with each branch connecting several stations in a bus
topology• To share the advantages from various topologies
1-12
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Balaganesh -Lincoln University
Categories of Networks
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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LAN• Usually privately owned• A network for a single office, building, or campus a few Km • Common LAN topologies: bus, ring, star • An isolated LAN connecting 12 computers to a hub in a closet
1-14
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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MAN• Designed to extend to an entire city• Cable TV network, a company’s connected LANs• Owned by a private or a public company
1-15
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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WAN• Long distance transmission, e.g., a country, a continent, the world • Enterprise network: A WAN that is owned and used by one company
1-16
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Balaganesh -Lincoln University
Internetwork• Internetwork (internet) : two or more networks are
connected by internetworking devices • Internetworking devices: router, gateway, etc. • The Internet: a specific worldwide network
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Balaganesh -Lincoln University
Internetwork Example• A heterogeneous network : four WANs and two LANs
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Network Vs Internet
Internet Network of network is called Internet
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Internet• Internet programming language• E-mail• SMS(short message service)• Social networking sites• Websites• Blog - Share your life's stories, videos and photos
• VOIP - Voice over Internet Protocol
• Podcast - type of digital media consisting of an episodic series of audio, video, PDF
• Rss(Really simple Syndication) - TechNet provides RSS feeds for its security bulletins, advisories, magazine features, and other security-related alerts for IT professionals.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
The Internet
• Internet is a network of interconnected computers that is now global
• Internet born in 1969 - called ARPANET• 1969 ARPANET was connection of computers
at UCLA, Stanford, UCSB, Univ. of Utah
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
The Advanced Research Projects Agency Network
• In 1969, the U.S. Defence Department funded a project to develop a network, which can withstand the bombing. Basically the idea was to develop a very secure network which can work even after a nuclear attack. This project was known as ARPANET.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Internet Connections
Various technologies available to connect a home computer to the Internet
Phone modem converts computer data into an analog audio signal for transfer over a telephone line, and then a modem at the destination converts it back again into data
Digital subscriber line (DSL) uses regular copper phone lines to transfer digital data to and from the phone company’s central office
Cable modem uses the same line that your cable TV signals come in on to transfer the data back and forth
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Internet Connections
Broadband A connection in which transfer speeds are faster than 768 kilobits per second
– DSL connections and cable modems are broadband connections
– The speed for downloads (getting data from the Internet to your home computer) may not be the same as uploads (sending data from your home computer to the Internet)
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Data
• Analog data– Voice– Images
• Digital data– Text– Digitized voice or images
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Modem
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Analog Signaling
• represented by sine waves
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time
(sec)
ampl
itude
(vol
ts) 1 cycle
frequency (hertz)= cycles per second
phase difference
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING Three Components of Data Communication
• Data– Analog: Continuous value data (sound, light, temperature)– Digital: Discrete value (text, integers, symbols)
• Signal– Analog: Continuously varying electromagnetic wave– Digital: Series of voltage pulses (square wave)
• Transmission– Analog: Works the same for analog or digital signals– Digital: Used only with digital signals
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Modem
• Anlog• Digital• Modulation
– Digital to analog conversion
• Demodulation– Analog to Digital ConversionModulation and demodulation is called Modem
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Modem Internet Connections• Dial-up connection via modem (56K)• Cable modems
– Network card and cable modem required– Always-on and 25 times faster than dial-up
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Faster Internet Connections• ISDN (Integrated Services Digital Network)– 64K or 128K– Always-on and expensive
• DSL (Digital Subscriber Line)– Up to 125 times faster than dialup
• DSS (Digital Satellite Service)– 500K
04/11/2023 Balaganesh -Lincoln University 32Need proximity to a telephone switching station
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
ISP (Internet Service Provider)
If you want to connect to the Internet, you need to subscribe via an Internet Service Provider. The ISP gives you a connection to the Internet either via your telephone line or via a special digital high speed line. An example of a popular ISP is AOL (America On-Line).
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Internet Service Provider (ISP)• Provides internet access to businesses, organizations and individuals
• Provides telecommunications equipment• User ID and password required• Connects you to backbone• E-mail account monthly fee• Should have local access telephone
numbers
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
SERVICES OF INTERNET
• WWW• FTP• Telnet• E-mail
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
What is the difference between the World Wide Web (WWW) and the Internet?
WWW is the acronym for the World Wide Web. It is also commonlyknown as ‘The Web’. The WWW is hypertext based information retrievaltool
• The World Wide Web (WWW) is just a small part of the Internet as a whole.
• The Internet, relates to all the hardware and software involved, and as well as including the WWW, also includes FTP (File Transfer Protocol – more about this later), email and newsgroups.
• The WWW is basically the text and pictures which you can view using your web browser, such as Microsoft Internet Explorer, or Netscape Navigator.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
World Wide Web Basics• Files interconnected via hypertext• Web pages make up a web site• Home Page• Links or hyperlinks• Web servers
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
FTP (File Transfer Protocol)
File Transfer Protocol, is an Internet utility software used to uploadand download files. It gives access to directories or folders on remotecomputers and allows software, data and text files to be transferredbetween different kinds of computers.
• FTP is just a way of transferring data from one place to another over the Internet. If is often used for downloading large files from a web site. You do not really need to know anything about how it works, in most cases you willclick on a link within a web page, and your web browser (such as Microsoft Internet Explorer) will take care of the FTP transfer for you, all you have to decide is where to store the file which you wish to download.04/11/2023 Balaganesh -Lincoln University 38
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
The basic objectives of FTP are
• to give flexibility and promote sharing of computer programs, files and data
• to transfer data reliably and more efficiently over network
• to encourage implicit or indirect use of remote computers using Internet
• to shield a user from variations in file storage systems among hosts
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Telnet (Remote Computing)
• Telnet (Remote Computing)Telnet or remote computing is telecommunication utility software,which uses available telecommunication facility and allows you tobecome a user on a remote computer. Once you gain access to theremote computer, you can use it for the intended purpose. TheTELNET works in a very step by step procedure. The commandstyped on the client computer are sent to the local Internet ServiceProvider (ISP), and then from the ISP to the remote computer thatyou have gained access. Most of the ISP provides facility to TELENETinto your own account from another city and check your e-mailwhile you are traveling or away on business04/11/2023 Balaganesh -Lincoln University 40
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
E-Mail (Electronic Mail)
E-mail or Electronic mail is a paperless method of sending messages,notes or letters from one person to another or even manypeople at the same time via Internet. E-mail is very fast compared tothe normal post. E-mail messages usually take only few seconds toarrive at their destination
Features of E-mail:• One-to-one or one-to-many communications• Instant communications• Physical presence of recipient is not required• Most inexpensive mail services, 24-hours a day and seven days a week• Encourages informal communications04/11/2023 Balaganesh -Lincoln University 41
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Voice Messaging
Voice MessagingIt is a new communication approach which is similar to electronic mail exceptthat it is audio message rather than text messages that are processed. A
senderspeaks into a telephone rather than typing, giving the name of the recipient
andthe message. That sender's voice signal is then digitalised and stored. The
systemcan then either deliver the message at a specified time in future or it can beretrieved from a database by the recipient.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
E-CommerceElectronic commerce or e-commerce as it is popularly known refers to thepaperless exchange of business information using Electronic Data
Interchange,Electronic mail, Electronic Bulletin Boards, Electronic Fund Transfer and othernetwork based technologies. Electronic Commerce (EC) not only automatesmanual process and paper transactions, but it also helps organisations to
moveinto a fully electronic environment and change the way they usually operate.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Internet Important Terms
• HTTP• URL• Hyperlink• Browser• Cookies• Internet cache• SECURITY04/11/2023 Balaganesh -Lincoln University 44
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
HTTP (Hypertext Transfer Protocol)
• HTTP stands for Hypertext Transfer Protocol. This is the language your web browser uses to request pages & graphics from the web server. You can see that your web browser is using the HTTP protocol when it is shown at the start of a web address such as http://www.yahoo.com
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
URL (Uniform Resource Locator)
• The URL (Uniform Resource Locator) is just another name for a web address.
• The URL consists of the name of the protocol (usually HTTP or FTP) followed by the address of the computer you want to connect to, e.g. a URL of “ftp://ftp.cdrom.com” would instruct your web browser to use the FTP protocol to connect to the computer called ftp.cdrom.com.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
World Wide Web Basics• URL– No spaces and Case sensitive– HTTP (Hypertext Transfer Protocol)
• HTML (Hypertext Markup Language)– .htm or .html file extension
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Document nameand filename
extensionFoldername
Web servername
Web protocolstandard
http://www.cnn.com/showbiz/movies.htm
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Network Addresses
Hostname A name made up of words separated by dots that uniquely identifies a computer on the InternetIP addressAn address made up of four one-byte numeric values separated by dots that uniquely identifies a computer on the Internet
Is there a correspondence between the parts of a hostname and an IP address?
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Domain Name SystemHost numberThe part of the IP address that specifies a particular host (machine) on the network Yes, but what is it?Domain nameThe part of a hostname that specifies a specific organization or groupTop-level domain (TLD)The last section of a domain name that specifies the type of organization or its country of origin
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Domain Name System
matisse.csc.villanova.edu
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Computer
name
Domain name TLD
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Domain Name System
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Figure 15.10 Top-level domains, including some relatively new ones
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Domain Name SystemOrganizations based in countries other than the United States use a top-level domain that corresponds to their two-letter country codes
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Figure 15.11Some of the top-level domain names based on country codes
Do you email
someonein anothercountry?
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Domain Name System
Domain name system (DNS) A distributed system for managing hostname resolutionDomain name serverA computer that attempts to translate a hostname into an IP address
Should the tables containing hostname/IP mappings be sorted or unsorted? Why?
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING Domain Name Addressing
• Domain names can include any number of parts separated by periods, however most domain names currently in use have only three or four parts.
• Domain names follow hierarchical model that you can follow from top to bottom if you read the name from the right to the left.
• For example, the domain name gsb.uchicago.edu is the computer connected to the Internet at the Graduate School of Business (gsb), which is an academic unit of the University of Chicago (uchicago), which is an educational institution (edu).
• No other computer on the Internet has the same domain name.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING Uniform Resource Locators
• The IP address and the domain name each identify a particular computer on the Internet.
• However, they do not indicate where a Web page’s HTML document resides on that computer.
• To identify a Web pages exact location, Web browsers rely on Uniform Resource Locator (URL).
• URL is a four-part addressing scheme that tells the Web browser:
What transfer protocol to use for transporting the file The domain name of the computer on which the file resides The pathname of the folder or directory on the computer on
which the file resides The name of the file
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Structure of a Uniform Resource Locators
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http://www.chicagosymphony.org/civicconcerts/index.htm
protocol
Domain name
pathname
filename
http => Hypertext Transfer Protocol
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Hyperlink
A hyperlink is a piece of text (or a graphic) on a Web page, which when clicked on will automatically:
- Take you to a different part of the same page- Take you to a different page within the Web
site
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
What is a web browser?
Web browsing applications include ‘Internet Explorer’ (from Microsoft) and ‘Netscape Navigator/Communicator’. In both cases there are many different versions, and you will find that the later versions offer much more versatility as well as a better range of built-in features. The web browser allows you to view web pages
04/11/2023 Balaganesh -Lincoln University 58
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
• What are cookies?• Some web sites can store hidden information about you on your hard diskusing cookies. This information is stored in small text file. Cookies can beuseful, for instance, a site may store your preferences about a web site, sothat when you re-visit the site your preferences can be accessedautomatically. Cookies are used by some web sites to identify you; this savesyou having to “log in” to the web site each time you visit.
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
What is an Internet cache?
Each time you display a web site within your web browser, a copy of theinformation (both text and pictures) is saved on your hard disk. The reasonfor this is that the next time you want to re-visit the site, the information isquickly loaded from the copy on your hard disk, rather than slowly from theactual Internet site.• As pictures are stored in the cache, if you are visiting a site which has manyseparate web pages, with say a company logo on each page, then allsubsequent pages from that site will load a little faster as the logo graphicswill load from the cache, not via the Internet
04/11/2023 Balaganesh -Lincoln University 60
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
SECURITY CONSIDERATIONS
• What is a digital certificate?• A digital certificate is used to encrypt information for secure transmissionacross the Internet. A digital certificate can be used to create a digitalsignature for an email, the signature guarantees the identity of sender, and italso ensures that the message cannot be tampered with in transit. A digitalcertificate can be purchased from a certificate authority such aswww.verisign.com who will verify your identity. Digital certificates are usedby Internet based shopping web sites to encrypt your credit card details sothey cannot be intercepted as they travel the Internet. You can view thedigital certificate for a secure web site by double clicking on the padlock inthe web browser status bar, e.g. https://www.paypal.com04/11/2023 Balaganesh -Lincoln University 61
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
• What is encryption?• Encryption is a means of 'scrambling' an email message. It is used to make
amessage more secure, so that only the intended recipient of the message willbe able to read the message. There are many means of enabling thisencryption, both via hardware and software. A famous encryption program iscalled PGP(Pretty Good Privacy)
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Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
• What is a firewall?• A fire wall consists of software and hardware protection against invasion
viathe Internet. In most larger companies any connection to the Internetautomatically goes through a firewall which would have been installed andcustomised by the companies technical IT team. In most cases you will beunaware of the firewall existence.
04/11/2023 Balaganesh -Lincoln University 63
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Internet vs Interanet
• Intranet is an internal private computer network or connection of one or more computer networks, whose use and access is restricted to an organization and its employees or members.. Such an intranet, mostly operates through a website, run by a local server, acting as a resource sharing medium. You could call it a scaled-down private Internet.
• Internet is a network of more than billion computers spread worldwide! It uses an ever improving set of Internet protocols (HTTP, FTP, SMTP, etc.) to transfer data. Unlike the intranet, the Internet and the information sharing service called the 'World Wide Web',
04/11/2023 Balaganesh -Lincoln University 64
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Modem Internet Connections• Dial-up connection via modem (56K)• Cable modems
– Network card and cable modem required– Always-on and 25 times faster than dial-up
04/11/2023 Balaganesh -Lincoln University 65
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Faster Internet Connections• ISDN (Integrated Services Digital Network)– 64K or 128K– Always-on and expensive
• DSL (Digital Subscriber Line)– Up to 125 times faster than dialup
• DSS (Digital Satellite Service)– 500K
04/11/2023 Balaganesh -Lincoln University 66Need proximity to a telephone switching station
Subject Name Code Credit HoursFUNDAMENTAL COMPUTER PRINCIPLE & PROGRAMMING
Internet vs Interanet
• Intranet is an internal private computer network or connection of one or more computer networks, whose use and access is restricted to an organization and its employees or members.. Such an intranet, mostly operates through a website, run by a local server, acting as a resource sharing medium. You could call it a scaled-down private Internet.
• Internet is a network of more than billion computers spread worldwide! It uses an ever improving set of Internet protocols (HTTP, FTP, SMTP, etc.) to transfer data. Unlike the intranet, the Internet and the information sharing service called the 'World Wide Web',
04/11/2023 Balaganesh -Lincoln University 67