AssignmentSubject: Computer NetworksSubject Code: ETIT 306

1. Why are protocols needed? 2. Why are standards needed? 3. What is the difference between Simplex, Half-duplex and Full duplex

channels? 4. What are the advantages of a multipoint connection over a point to point

connection?5. Assume 6 devices are arranged in a mesh topology. How many cables are

needed? How many ports are needed for each device? 6. What are the two types of line configuration?7. Draw a hybrid topology with a ring backbone and three bus networks.8. Define LAN, MAN and WAN.9. You have two computers connected by an Ethernet hub at home. Is this a LAN,

a MAN, or a WAN? Explain your reason.10.What are header and trailers and how do they get added and removed? 11.The transport layer creates a communication between the source and

destination. What are the three events involved in a connection? 12. Explain ISO/OSI reference model. 13.What is the difference between a port address, a logical address, and a physical

address?14. What are the two reasons for using layered protocols?15. In which of the 7 layers of OSI will a service handling conversion of

characters is from EBCDIC to ASCII be normally implemented ?16.Explain the topologies of the network. 17.Match the following to one or more layers of the OSI model:

(a) Establishes, manages and terminate sessions(b) Format and code conversion services(c) Ensures reliable transmission of data(d) Log-in and Log-out procedures(e) Provides independence from differences in data representation(f) Flow control(g) Route determination(h) Provides access for the end user(i) Defines Frames(j) Reliable process to process delivery

(k) Provides user services such as E-mail and File transfer 18.Explain coaxial cable & fiber optics. 19.Explain two major categories of transmission media.20. Differentiate between:

(i) Baseband co-axial cable and broad band coaxial cable (ii) Optical fibre and twisted pair

21. The physical layer service is a non-confirmed service. Assume that some bits of data are lost during transmission over physical media, which layer will detect the loss and take some remedial measures. Explain any one method clearly depicting how this operation is performed.

22. A binary signal is sent over a 3-khz channel whose signal-to-noise ratio is 20 db. Calculate the maximum achievable data rate ?

23.Differentiate between Circuit, Packet and message switching? 24.What is ISO-OSI reference model ? Compare it with TCP/IP reference model.

Why TCP/IP reference model is more popular than OSI model ? Which layer is used for the following : (i) Route packets (ii) Convert packets to frame (iii) Detect and correct errors (iv) Run services like FTP, Telnet etc.

25. Where is the special IP address 127.0.0.0. used ?26. Convert the following IP addresses from dotted decimal to binary notation:

(a) 114.34.12.8(b) 127. 24.6.8(c) 232.34.2.1

27.Convert the following IP addresses from binary to dotted decimal notation:(a) 01111111 11110000 01100111 11111001(b) 10101111 11000111 11111000 00011101(c) 11100000 11110111 11000111 01111101

28.In a block of addresses, we know that IP address of one host is 182.44.82.16/26. What are the first address (network address) and the last address in the block.

29. Find the netid and the hosted of the following IP addresses:(a) 117.34.3.8(b) 132.57.8.6(c) 207.3.54.12

30.Find the class of the following IP addresses:(a) 237.14.2.1(b) 114.34.2.8

31.Find the range of addresses in the following blocks:(a) 200.17.21.128/27(b) 17.34.16.0/23

32.An organization is granted the block 211.17.180.0/24. The administrator wants to create 32 subnets.(a) Find the subnet mask(b) Find the number of addresses in each subnet(c ) Find the first and last addresses in subnet 1.(d) Find the first and last addresses in subnet 32.

33.What is the address space in the following systems.(a) A system with 16 bit addresses(b) A system with 64 bit addresses(c ) A system with 128 bit addresses

34. An address space has a total of 1024 addresses. How many bits are needed to represent an address.

35.What are the responsibilities of data link layer? 36.Mention the types of errors. 37.What is sliding window protocol ? Differentiate between stop-and wait ARQ

and Go-back-N protocol.38.How a single bit error is different from burst error? 39.What is Hamming and minimum Hammimg distance. 40.What is the Hamming distance for each of the following codewords:

(a) d(10000, 01000)(b) d(10101, 10010)(c) d(1111, 1111) (d) d(0000, 0000)

41.Give the equivalent binary word for the polynomial x8+x2+x+1.42.Mention the types of error correcting methods. 43.Define flow control. 44.Define piggybacking and its usefulness. 45.Compare flow control with error control. 46.Explain 1-persistent, p-persistent and 0-persistent CSMA giving strong and

weak points of each. 47.Explain network equipment used in wired-LANS and explain the function of

Hub, Switch, and bridge.48. Write short note on any four of the following:

(a) Token ring (b) Various fields in Ethernet frame format (c) Difference between congestion control and QoS(or Quality of service)

(d) FDDI (e) Traffic shaping using token bucket algorithm

(f) CSMA/CD49.Why do we need a DNS system when we can directly use an IP address? 50.What are the three domains of a domain name space.51.What are the advantages of cell switching that is used in ATM?52. Outline and discuss the main fields in Ethernet IEEE 802.3 frame. What are

the main objectives of preamble?53. Write short note on any four of the following:

(a) The ATM reference model (b) HDLC (c) Network Topologies and their uses.

(d) Wireless networks.54.Differentiate between static and dynamic channel allocation.55. List out the main responsibilities of the network layer.56.Give two examples of a ‘collision-free’ protocol?57. Why is IP called ‘best-effort delivery’ protocol?58. What is a transparent bridge?59. what are the two sub layers of data link layer called ?60. What are the other names of IEEE 802.11 protocol or standard?61.What is a minimum data size of an Ethernet frame ?62. Explain pure-ALOHA and slotted- ALOHA systems.Give the expression for

throughout for each,clearly explaining the various terms.63. What do you mean by link to link layers of OSI reference model? Explain

their functions briefly?64.Write a short note on ISDN?65. Explain the working of 3 bit sliding window protocol with suitable

example.66. Explain the following ARQ techniques in detail

1. Stop and wait ARQ 2. Selective repeat ARQ

67.Why do data link layer protocols position the checksum in the trailer and not in the header?

68.Compare the maximum window size in go-back-N and selective-repeat ARQs.69. Why does ATM use the cell of small and fixed length?70.What is meant by congestion? And why the congestion occurs in network? 71.What is meant by quality of service and What are the two categories of QoS

attributes? List out the user and network related attributes? 72.Explain leaky bucket and token bucket algorithms.