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Code No: R05310504
Set No. 1
III B.Tech I Semester Regular Examinations, November 2007
COMPUTER NETWORKS
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. Write short notes on the following:
(a) Client server mo del
(b) MAN
(c) Interfaces and services. [4+6+6]
2. (a) Discuss in detail about space division switches?
(b) With a neat diagram explain ISDN system for home use? [8+8]
3. (a) Explain one -bit sliding window protocol. Give the advantages and disadvan-
tages of one-bit sliding window protocol?
(b) Discuss the services provided by the data link layer to the network layer?
[8+8]
4. (a) What is the prime di erence between a token bus and a token ring?
(b) A large population of ALOHA users manages to generate 50 requests/sec,
including both originals and retransmissions. Time is slotted in the units of
40 msec.
i. What is the chance of success on the rst attempt?
ii. What is the probability of exactly k collisions and then a success?
iii. What is the expected number of transmission attempts needed? [4+12]
5. De ne route. Why routing algorithm is required. Routes can be predetermined
and then use them when required (or) Routes can be determined when needed and
use them immediately. First method is proactive and second metho d is reactive.
Which one is preferred for wired networks? Justify your answer. [16]
6. (a) How Tunneling helps in connecting two di erent networks?
(b) How routing in inter-network is di erent from routing in subnet? [8+8]
7. (a) What is the purpose of sequence numbers in TCP Segment?
(b) Why padding is required for TCP Segment?
(c) Write short notes on TCP timers. [4+4+8]
8. (a) What is security? What is network security? What is information security?

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Code No: R05310504
Set No. 1
(b) What are the Pros and Cons of providing security?
(c) Who are the people who cause security problems? [6+5+5]

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Code No: R05310504
Set No. 2
III B.Tech I Semester Regular Examinations, November 2007
COMPUTER NETWORKS
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) Give a detailed description of the Novell Netware reference model.
(b) With suitable examples explain simplex, half-duplex & full-duplex communi-
cation. [10+6]
2. (a) Discuss in detail about asynchronous communication?
(b) Discuss in detail about broad band ISDN? [8+8]
3. (a) Discuss the error control technique which is commonly used in data network.
What value of N is used in go-back-N ARQ technique used in ARPANET and
why?
(b) Imagine that you are writing the data link software for a line used to send
data to you, but not from you. The other end uses HDLC, with a 3-bit
sequence number and a window size of seven frames. You would like to bu er
as many out of sequence frames as possible to enhance e ciency, but you are
not allowed to modify the software on the sending side. Is it possible to have
a receiver window greater than one, and still guarantee that the protocol will
never fail? If so, what is the largest window that can be safely used? [8+8]
4. (a) Discuss about MAC addresses?
(b) Explain about a bit-map collision free protocol? [8+8]
5. (a) What is Multicasting. How it is di erent from broadcasting. How do you
construct a multicast tree. Explain with an example.
(b) What are the applications of multicasting. [10+6]
6. (a) How congestion is controlled in ATM?
(b) Explain ATM LAN emulation. [8+8]
7. (a) What are the applications which use connection oriented service and which
use connection less service? Explain?
(b) What is the type of service that is required for uncompressed audio & video.
Explain?
(c) What is the type of service that is required for compressed audio & Video?
Explain? [6+5+5]

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Code No: R05310504
Set No. 2
(b) What is the role played by di erent layers in providing security? [8+8]

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Code No: R05310504
Set No. 3
III B.Tech I Semester Regular Examinations, November 2007
COMPUTER NETWORKS
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) Compare point -to-point channels with broadcast channels along with suitable
examples?
(b) A collection of ve routers is to be collected in a point-to-point subnet. Be-
tween each pair of routers, the designers may put a high speed line, a medium-
speed line, a low-speed line, or no line. If it takes 100ms of computer time
to generate and inspect each topology, how long will it take to inspect all of
them to nd the one that best matches the expected load? [8+8]
2. (a) Compare the two methods of serial transmission. Discuss the advantages and
disadvantages of each?
(b) With a neat diagram explain about Kno ckout switch? [8+8]
3. (a) Discuss the error control technique which is commonly used in data network.
What value of N is used in go-back-N ARQ technique used in ARPANET and
why?
(b) Imagine that you are writing the data link software for a line used to send
data to you, but not from you. The other end uses HDLC, with a 3-bit
sequence number and a window size of seven frames. You would like to bu er
as many out of sequence frames as possible to enhance e ciency, but you are
not allowed to modify the software on the sending side. Is it possible to have
a receiver window greater than one, and still guarantee that the protocol will
never fail? If so, what is the largest window that can be safely used? [8+8]
4. What is a token? Discuss the protocol of token ring LAN in general. Discuss with
example how priority is implemented in a token ring LAN? [16]
5. What is non- adaptive routing. Explain any two non- adaptive routing algorithms.
[16]
6. Explain Network layer in ATM. [16]
7. (a) What are the similarities and di erences between Data Link layer and Trans-
port layer?
(b) Explain addressing at Transport layer? [6+10]
8. What is Authentication? How it is di erent from Authorization? Explain in brief
di erent Authentication protocols with their relative merits and demerits. [16]

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Code No: R05310504
Set No. 4
III B.Tech I Semester Regular Examinations, November 2007
COMPUTER NETWORKS
( Common to Computer Science & Engineering and Information
Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) Compare and contrast WAN and Internet
(b) What are the various types of network topology? What are the implications
of having di erent topologies? [6+10]
2. (a) Give a comparison of semiconductor diodes and LEDs as light sources?
(b) Discuss about wireless communication in detail? [6+10]
3. (a) Discuss the error control technique which is commonly used in data network.
What value of N is used in go-back-N ARQ technique used in ARPANET and
why?
(b) Imagine that you are writing the data link software for a line used to send
data to you, but not from you. The other end uses HDLC, with a 3-bit
sequence number and a window size of seven frames. You would like to bu er
as many out of sequence frames as possible to enhance e ciency, but you are
not allowed to modify the software on the sending side. Is it possible to have
a receiver window greater than one, and still guarantee that the protocol will
never fail? If so, what is the largest window that can be safely used? [8+8]
4. (a) Discuss about the le key assumptions in case of dynamic channel allocation
in LANs and WANs?
(b) Discuss in detail the working of token bus? [8+8]
5. How bu ering at receiver can help in solving out of order delivery of packets. What
are the limitations of it. What are the applications for which this strategy is suitable
and why. What are the applications for which this strategy is not suitable and why.
Explain. [16]
6. (a) What are the message types used by ICMP? Explain.
(b) Explain the network protocols.
i. ARP
ii. RARP. [6+10]
7. (a) Explain the protocol scenarios for releasing a connection.
(b) What is the relation between NSAP & TSAP? [12+4]
8. (a) What is security? What is network security? What is information security?

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Code No: R05310504
Set No. 4
(b) What are the Pros and Cons of providing security?
(c) Who are the people who cause security problems? [6+5+5]