CS Computer Networks Two Marks Questions With Answers Anna University, Chennai. Anna_University,_Chennai_logo. UNIT I. 1. Explain ISO/OSI . CS COMPUTER NETWORKS TWO MARK QUESTIONS WITH ANSWERS ANNA UNIVERSITY QUESTION BANK BY SELVAM COLLEGE OF. A Computer network is a number of computers interconn this is for 2 marks and 16 marks question papers for data communication. Copyright: Attribution CSComputer Networks – Anna University Engineering Question Bank 4 U. Uploaded Mobile Communication 2-MARK Questions and Answers. Uploaded .

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What is mean by data communication? Data communication is questoons exchange of data in the form of 1s and 0s between two devices via some form of transmission medium such as a wire cable. What are the three criteria necessary for an effective and efficient network? The most important criteria are performance, reliability and security. Security issues include protecting data from unauthorized access and viruses.

What are the three fundamental characteristics determine the effectiveness of the data communication system? The effectiveness of the data communication system depends on 3 fundamental characters: The system must deliver data to the correct destination. The system must deliver data accurately. The system must deliver data in a timely manner. What are the advantages of distributed processing?

Why are protocols needed?

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In networks, communication occurs between the entities in different systems. Two entities cannot just send bit streams to each other and expect to be understood. For communication, the entities must agree on a protocol. A protocol is a set of rules that govern data communication.

Why are standards needed? Co-ordination across the nodes of a network is necessary for an efficient communication. If there are no standards, difficulties arise. A standard provides a model or basis for development to which everyone has agreed. For n devices in a network, what is the number of cable links required for a mesh and ring topology? What is the difference between a passive and an active hub? An active hub contains a repeater that regenerates the received bit patterns before sending them out.

A passive hub provides a simple physical connection between the attached devices. Page 1 of 24 9. Distinguish between peer-to-peer relationship and a primary-secondary relationship. P ee r -t o-peer relationship: All the devices share the link equally. P r i m ary-secondary relationship: One device controls traffic and the others must transmit through it.

Assume 6 devices are arranged in a mesh topology. How many cables are needed? How many ports are needed for each device? Group the OSI layers by function.


The seven layers of the OSI model belonging to three subgroups. Physical, datalink and network layers are the network support layers; they deal with queetions physical aspects of moving data from one device to another. Session, presentation and application layers are the user support layers; they allow interoperability among unrelated software systems.

The snd layer ensures end-to-end reliable data transmission. What are header and trailers and how do they get added and removed?

Each layer in the sending machine adds its own information to the message it receives from the layer just above it and passes the whole package to the layer just below it.

This information is added in the form of headers or trailers. Headers are added to the message at the layers 6,5,4,3, and 2. A trailer is added at layer2.

Anna University Chennai CS – COMPUTER NETWORKS(Regulation ) model question papers

At the receiving machine, the headers or trailers attached to the data unit at the corresponding sending layers are removed, and actions appropriate to that layer retaken. The transport layer creates a communication between the source and destination. What are the three events involved in a connection? Creating a connection involves three steps: What is the DC component? Direct current is a zero-frequency signal with constant amplitude. In the NRZ-L sequence, positive and negative voltages have specific meanings: Instead, the receiver looks for changes from one level to another as its basis for recognition qhestions 1s.

Using HDB3, encode the bit stream Assume the number of 1s so far is odd and the first 1 is positive. What are the functions of a DTE? What are the functions compuger a DCE? Data terminal equipment is a device that is an information source or an information sink. It is connected to a network through a Anv. Data circuit-terminating equipment is a device wnd as an interface between a DTE and a network.

What does the electrical specification of EIA describe? The data must be transmitted using NRZ-L encoding. Discuss the mode for propagating light along optical channels. There are two modes for propagating light along optical channels, Quesitons ul t i m ode: Multiple beams from a light source move through the core in different paths. Fiber with extremely small diameter that limits beams to a few angles ,resulting in an almost horizontal beam. The phenomenon related to the bending of light when it passes from one medium to another.

How are the guided media differing from unguided transmission media? Guided transmission media Unguided transmission media. What are the netaorks of optical fiber as a transmission medium? The disadvantages of optical fiber are Very expensive. Installation and maintenance is difficult. What are the criteria used to evaluate transmission medium? The criteria used to questioons transmission medium are Throughput Propagation speed Propagation time Wavelength Give the relationship between propagation speed and propagation time?


Network r opagation speed is the distance, a signal or a bit travel through a medium in one second. Explain cross talk and what is needed to reduce it? Effect of one wire on another is called as cross talk. One wire will be the sending antenna and the other wire will be the receiving antenna. We can use the shielded twisted pair cable or coaxial cable for transmission, which contains metal foil to reduce cross talk.

What are the responsibilities of data link layer? Specific responsibilities of data link layer include the following. Mention the types of errors. There are 2 types of errors a Single-bit error. Define the following terms. Means that 2 or more bits in the data unit have changed from 1 to 0 neyworks 0 to 1. It is the error detecting mechanism, which means a shorter group of bits or extra bits may be appended at the destination of each unit.

List out the questins detection methods. There are 4 types of redundancy checks are used in data communication.

Write short notes on VRC. The most common and least expensive mechanism for error detection is the vertical redundancy check VRC often called a parity check. Write short notes on LRC. In longitudinal redundancy check LRCa block of annd is divided into rows and a redundant row of bits is added to the whole block. Write short notes on CRC.

The third and most powerful of the redundancy checking techniques is the cyclic redundancy checks CRC CRC is based on binary division.

Here sequence of redundant bits, called the CRC remainder is appended to the end of data unit. Write cz2302 notes on CRC generator. A CRC generator uses a modulo-2 division.

Page 4 of 24 Write short notes on CRC checker. A CRC checker functions exactly like a generator.