Computer Network Imp Questions

DRONACHARYA COLLEGE OF ENGG GR. NOIDA COMPUTER NETWORK

Subject Code : TCS-602

CSE/IT VIth

1. a) Explain OSI reference model. Clearly indicate function of each layer. Compare OSI model with TCP/IP protocol suite. Write merit and demerits of both,. b) Explain topology of computer networks. Define categories of network. c) Differentiate between bit rate and baud-rate . A modem constellation diagram has data point at coordinate : (1,1), (1,-1),(-1,1) and (-1,-1). How many bps can modem with these parameters achieve at 1200 baud? 2. (a) What is the role of transmission media in network. Explain guided & unguided media. Also write details of fiber optical cable used. (b) Differentiate message, circuit & packet switching. Explain services ,architecture and use of ISDN. (c) (c). I n a certain communication channel, the signal power is 100W and the noise power is 10W. In order to send information at the rate of 10 Kbps, what is required bandwidth? 3 (a) What do you mean by character & bit stuffing. Give examples. Why minimum size of frame is required in a LAN? (b) Explain HDLC, SDLC, BSC, SLIP, LCP, NCP protocols. (c) For data 0001110101 draw Manchester & diff. man. Coding. 4. (a) The codeword is received as 1100 1001 01011. Check whether there are errors in the received code word, if the divisor is 10101.(The divisor corresponds to the generator polynomial). (b) A seven bit hamming code is received as 1110101. What is the correct code? (c) Write the steps to compute the checksum in CRC code. Calculate CRC for the frame 110101011 and the generator polynomial =x4+x+1 & write the transmitted frame.

5. (a) A bit stream 10011101 is transmitted using the standard CRC method . The generator polynomial is x3+1. Show the actual bit string transmitted. Suppose the third bit from left is inverted during transmission .Show that the error is detected at the receiver’s end. (b) A bit string 0111101111101111110 , needs to be transmitted at the data link layer. What is the string actually transmitted after bit stuffing. (c) A channel has a bit rate of 4 kbps & propagation delay of 20 msec. For what range of frame sizes does stop and wait gives an efficiency of at least 50%. 6. (a) What is need of min. frame size ? If it is 64 bytes then calculate the loss of bandwidth for 100 Mbps Ethernet Network? (b) Fast Ethernet has the same 64 bytes min. frame size but can get bits out ten times faster. How is it possible to maintain the same min. frame size? How much bandwidth loss will occur in this case? (c) Why is the channel throughput doubled in slotted ALOHA compared to pure ALOHA? 7. (a) Explain CRC generator. Explain hamming code with an example. (b) Explain sliding window protocol & piggybacking with suitable example. 8. (a) Derive formula for pure & slotted ALOHA. (b) Explain CSMA/CD & collision free protocols. (c) Compare 802.3, 802.4, 802.5. Explain types of bridges. 9. (a) Explain distance vector routing with an example. Compare with Dijkstra algorithm. (b) A computer on a 6-Mbps network is regulated by token bucket. Token bucket filled at a rate of 1 Mbps. It is initially filled to a capacity with 8 megabits. How long can computer transmit at the full 6 Mbps?

10. (a) Explain congestion control & prevention methods. (b) An ATM network uses a token bucket scheme for traffic shaping. A new token is put into bucket every 5 microsec. What is the max. sustainable net data rate(excluding the header bits)? 11. (a) Explain use of tunneling & functioning of firewalls. (b) Explain ARP, RARP, IPv4 & IPv6 with their frame format. Explain IPv4 & IPv6 addresses .Compare both. 12. (a) Explain special addresses used in IPv4 . Explain quality of services w.r.t. transport layer. (b) Explain transport layer primitives & Berkely Unix primitives. (c) Show by calculations how many network each IP address class can have with one example. 13. (a) Explain three way handshake protocols. (b) Explain TCP & UDP protocols. (c) A class B network on internet has a subnet mask of 255.255.240.0. What is the max. no. of hosts per subnet? 14. (a) Explain silly window syndrome, Jacobson and Nangle algorithm. (b) Perform the subnetting of the following IP address 160.111.X.X. Original subnet mask is 255.255.0.0 , number of subnets 6(six) 15. (a) Explain multimedia , JPEG, MPEG. (b) Explain DNS , SMTP, MIME, FTP, TFTP. (c) How do contention-free protocols differ from contention-oriented protocols? Discuss any one protocol of contention –free category.

16. (a) Explain delivery protocols,X.25, Frame relay, Jitter control & ATM. (b) Explain URL, WWW, HTTP & WAP. 17. (a) Explain wireless LAN, Novell netware & FDDI.. (b) How is bridge different from a repeater? What are the advantage and disadvantages of each? State with reason whether an LAN can be extended to any size by increasing the number of repeaters or not? 18. (a) Explain flooding, count to infinity problem & split horizon problem. (b) Explain leaky bucket & token bucket algorithm suitable diagram. 19. (a) A company is granted a site address 201.70.64.0.The company needs six subnets. Design the subnets. (b) What is count-to-infinity problem? How is it addressed in link state routing protocol? For following subnet, distance vector routing is used and the vectors that have just come in to route C: from B(5,0,8,12,6,2); from D:(16,12,6,0,9,10); and from E:(7,6,3,9,0,4). The measured delays to B,D,and E are 6,3, and 5 respectively. What is C’s new routing table? Give both the outgoing line to use and the expected delay? 20. (a) An IP packet has arrived with the first few hexadecimal digits as shown below: 45000028000100000102………………… How many hops can this packet travel before being dropped? The data belong to which upper layer protocol? (b) Explain DES , Triple DES & RSA with suitable examples .Compare Secret and Public key algorithms.