Indira Gandhi National Open University (IGNOU) 2005 Diploma Computer Applications CS09 (S) Data Communications and Networking - - Question Paper

ADCA / MCA (II Yr)
Term-End exam

December, 2005

CS09 (S): Data Communications and Networking

Time: three hours
Maximum Marks: 75

Note : ques. No. one is compulsory. ans any 3 ques. from the rest.
1. (a) discuss the 3 general principles of congestion control. (3)

(b) List the different services offered by BISDN. (3)

(c) A binary signal is sent over a three kHz channel whose signal to noise ratio is 20 dB. What is the maximum achievable data rate ? (3)

(d) explain 802-3 frame format. discuss its different fields. (4)

(e) Dfferentiate datagrams and virtual circuits. (5)

(f) Make the timing diagram of Manchester coding of bit stream : 1010000111 and mention its advantages over other coding schemes. (3)

(g) Television channels are six MHz wide. How many bits/sec can be sent, if 8 level digital signals are used ? presume the channel is noiseless. (4)

(h) discuss the RSA algorithm used in cryptography. (5)

2. (a) Derive the throughput expression for Aloha and Slotted Aloha. (6)

(b) What is the advantage of differential pulse code modulation over pulse code modulation ? How is digital transmission done through PCM ? explain. (6)

(c) What is 'bit stuffing' ? Why is it used ? Illustrate through an example. (3)

3. (a) The data b(t) consists of the bit stream : 001010011010. presume that the bit rate fb is equal to the canier frequency fo and sketch VBPSK(t). (3)

(b) What is a Subnet ? How do you implement subnetting ? discuss through an example. (6)

(c) What is count infinity issue ? How does it happen in distance vector routing algorithm ? Illustrate through an example. (6)

4. (a) Make a comparison ol channel utilization vs. load for different random access protocols. llustrate through a diagram. (7)

(b) A four mbps token ring has a token holding time value of 10 m sec. What is the longest frame that can be sent on this ring ? (5)

(c) List 3 differences ranging from IPv4 and IPv6. (3)

5. (a) Briefly define the token bucket algorithm through a proper illustration. How is it various from leaky bucket algorithm ? (10)

(b) In a network that has a maximum TPDU size of 128 k bytes. a maxrmurn TPDU lifetime of 30 sec, and an eight bit sequence number, what is the maximum data rate per connection ? (5)

6. Write short notes on any three: (15)

(a) SNMP protocol
(b) Electronic mail
(c) Network news transfer protocol
(d) Hyper text transfer protocol

Earning:   Approval pending.