DATA COMMUNICATION NETWORKS APRIL 2015

Month and Year of Examination:  April 2015

Paper: Data Communication and Networks.

Section- A (2 X 10 = 20)

1. List the components of data communication.

Ans: The basics components or elements of data communication system are as follows:

• Message
• Sender
• Receiver
• Medium or Communication Channel
• Encoder and Decoder

2. Define Half-Duplex Mode.

(ans:  A mode of communication in which a device can either transmit or receive data across a communications channel, but not both simultaneously. The capability for data transmission in only one direction at a time.)

3. What is LAN?

(ans: A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link to a server. LAN encompasses computers and peripherals connected to a server within a small geographic area such as an office building or home. Computers and other mobile devices can share resources such as a printer or network storage.)

4. Write a note on: Parallel Transmission.

(ans: Within a computing or communication device, the distances between different subunits are too short. Thus, it is normal practice to transfer data between subunits using a separate wire to carry each bit of data. There are multiple wires connecting each sub-unit and data is exchanged using a parallel transfer mode. This mode of operation results in minimal delays in transferring each word.)

5. What is MODEM?

(ans: a combined device for modulation and demodulation, for example, between the digital data of a computer and the analogue signal of a telephone line.) or (modulator-demodulator. A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms.)

6. Define: Burst Error.

(ans: In telecommunication, a burst error or error burst is a contiguous sequence of symbols, received over a data transmission channel, such that the first and last symbols are in error and there exists no contiguous subsequence of m correctly received symbols within the error burst.)

7. What is meant by Multiplexing?

(ans: In telecommunications and computer networks, multiplexing is a method by which multiple analog message signals or digital data streams are combined into one signal over a shared medium. The aim is to share an expensive resource. The multiplexed signal is transmitted over a communication channel, which may be a physical transmission medium (e.g. a cable). The multiplexing divides the capacity of the low-level communication channel into several high-level logical channels, one for each message signal or data stream to be transferred)

8. What is FDDI?

(ans: FDDI (Fiber Distributed Data Interface) is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network(LAN) that can extend in range up to 200 km (124 miles). The FDDI protocol is based on the token ring protocol.)

9. Define: Circuit Switching.

(ans: Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate.)

10. Write a note on Broadband ISDN.

(ans:  The telecommunication industry expected that digital services would follow much the same pattern as voice services did on the public switched telephone network and conceived an end-to-end circuit switched services, known as Broadband Integrated Services Digital Network (B-ISDN).)

11. What is meant by Router?

             ( ans: Routers are small physical devices that join multiple networks together. In packet-   switched networks such as the Internet, a router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. )

12. What is WWW?

( ans: Collection of internet resources (such as FTP, TELNET, USENET), hyperlinked text, audio, and video files, and remote sites that can be accessed and searched by browsers based on standards such as HTTP and TCP/IP)

Section- B (5 X 5 = 25)

13. Write Short notes on: Layers in OSI model.

14. Discuss briefly on: Serial Transmission.

15. Discuss any TWO guided transmission media.

16. Write short notes on: Ethernet.

17. Distinguish between Connection Oriented and Connectionless Services.

18. Discuss about ATM Protocol.

19. Write Short notes on: Bridges and Gateways.

Section- C (3 X 10 = 30)

20. Describe various Network Topologies.

21 Explain about Unguided Transmission Media used in Computer Networks.

22. Describe in detail, Token Bus and Token Ring.

23. Explain about X.25 Layers.

24. Discuss in detail, any ONE Routing Algorithm.