Data Communication and Computer Network -Practice Questions

MCS-042

 

Question 1:

(a) What are the main differences between connectionless and connection oriented communication?

(b) What are the essential differences between packet switching and message switching? Explain with   the help of a suitable diagram.

Question 2:

A system has 𝑛-layer protocol hierarchy. Applications generate message of length M bytes. At each of the layers, an h byte header is added. What fraction of the network bandwidth is filled with headers?

Question 3:

State the Nyquist theorem. For what kind of physical medium it is applicable? Will it work for a noisy Channel?

Question 4:

Define the throughput expressions of Aloha and Slotted Aloha. Also draw throughput Vs load graphs for the above protocols.

Question 5:

(a) Explain hidden station and exposed station problems in WLAN protocols with the help of an illustration. What is the limitation of CSMA protocol in resolving the above problems? Explain the use of virtual channel sensing method as a proposed solution.

(b) Sketch the differential Manchester encoding for the bit stream: 0011111010111. Assume the line is initially in the low state.

Question 6:

Draw the Ethernet frame format and explain its fields. Is there any limitation on a maximum and minimum frame size of Ethernet frame? Explain.

Question 7:

How does the Border Gateway. Protocol work? Explain it with the help of a diagram. How does it resolve the count to infinity problem that is caused by other distance vector routing-algorithms?

Question 8:

Draw the header format of TCP and explain the followings fields: ACK bit, RST bit & PSH bit, and Flags.

Question 9:

Explain the window management scheme in TCP through an illustration.

Question 10:

Discuss the Silly Window Syndrome which cause degradation of TCP performance. What is the proposed solution? Explain.

Question 11:

Explain the terms: bit rate, baud rate and bandwidth with the help of an example. Also draw modulation schemes for the followings: (i) QPSK (ii) QAM-16 and describe.

Question 12:

What are the differences between leaky bucket and token bucket algorithm? How is token bucket algorithm is implemented? Explain.

Question 13:

How does DES work? Explain.