Test Papers / Previous Question Papers of IGNOU CS09 Data Communications and Networking June 2003

ADCA / MCA (II Yr)
Term-End Examination

June, 2003

CS09 : Data Communications and Networking

Time: 3 hours
Maximum Marks: 75

1. i. Explain the principle of operation of CRC error detection method. Through an example, show how: (6) a. The error detection bits are generated.
b. The received frame is checked for transmission errors.
Use the generator polynomial for X⁴ + x³ + 1.

ii. State the meaning of the following IP addresses: (3)
a. An address with a net id of all 0s.
b. An address with a net id of all 1s.
c. An address with a host id of all 0s.

iii. With the aid of an example, explain why subnet was introduced. Hence, state the meaning of a subnet router and an address mask. (7)

iv. With the aid of a diagram, explain how does an Internet congestion algorithm work. (8)

v. Draw a space division three stage switch. There are 18 inputs and 20 outputs. Stage 1 has 3 switches, Stage 2 has two switches and Stage 3 has four switches. How many cross points are needed to compare this to a system using just one crossbar? (6)

2. Differentiate between the following: (15)
i. AAL Protocols
ii. ARP and RARP
iii. Manchester and Differential Manchester encoding techniques with example

3. i. Answer the following questions as applied to token ring protocol: (9)

a. How is the start and end of a frame detected?
b. The role of a token, monitor, priority and reservation in the access control bits.
c. The role of A and C bits in the frame status field.

ii. What is the advantage of QAM over ASK or PSK? Draw a 8 QAM constellation diagram with 2 amplitude and four phases. (6)

4. i. Draw an IP header format and explain the following (9)
a. Traffic Class
b. Payload length
c. Next header

ii. State why 4B/5B encoding is used in FDDI LANs rather than Differential Manchester encoding. (6)

5. i. Through a diagram explain the TCP connection management procedure both in normal case and collision case. Also list the states(with their meanings) used in TCP connection management finite state machine. (9)

ii. State the reason why classless inter domain routing was introduced. (6)

6. i. Define the following terms (10)
a. Transponder
b. Source routing bridge
c. Tunnelling
d. Bit Stuffing
e. Wave division multiplexing

ii. Explain the concept of binary exponential backoff algorithm. (5)