COMPUTER NETWORKS Questions Bank 2014

Anna University, Chennai

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16 MARKS QUESTIONS&KEYS (COMPUTER NETWORK) UNIT-1

1. Explain ISO/OSI reference model.

_ Physical layer

_ Data link layer

_ Network layer

_ Transport layer

_ Session layer

_ Presentation layer

_ Application layer

2. Explain the topologies of the network.

_ Mesh topology

_ Star topology

_ Tree topology

_ Bus topology

_ Ring topology

3. Explain the categories of networks.

_ Local Area Network(LAN)

_ Metropolitan Area Network(MAN)

_ Wide Area Network(WAN)

4. Explain coaxial cable & fiber optics.

_ Coaxial cable

_ Coaxial cable standards

_ Coaxial cable connectors

_ Fiber optics

_ Propagation modes

_ Fiber sizes

_ Cable composition

_ Light sources for optical cable

_ Fiber optic connectors

_ Advantages & disadvantages of optical fiber

5. Explain line coding (digital to digital conversion).

_ Unipolar

_ DC component

_ Synchronization

_ Polar

_ Non return to zero(NRZ)

_ NRZ-L

_ NRZ-I

_ Return to zero

_ Biphase

_ Manchester

_ Differential Manchester

_ Bipolar

_ Alternate Mark Inversion(AMI)

_ Bipolar 8-zero substitution(B8ZS)

_ High-Density Bipolar 3(HDB3)


UNIT II

1. Explain error detection and error correction techniques.

_ Types of errors

_ Single bit error

_ Burst error

_ Error detection

_ Vertical redundancy check(VRC)

_ Longitudinal redundancy check(LRC)

_ Cyclic redundancy check(CRC)

_ Checksum

_ Error correction

_ Single-bit error correction

_ Hamming code

_ Burst error correction

2. Explain error control mechanism.

_ Stop and wait ARQ

_ Sliding window ARQ

_ Go back-n

_ Selective-reject

3. Explain the flow control mechanism

_ Stop and wait

_ Sliding window.

4. Explain the timers and time registers in FDDI.

Time registers

_ Synchronous allocation(SA)

_ Target token rotation time(TTRT)

_ Absolute maximum time(AMT)

_ Timers

_ Token rotation timer(TRT)

_ Token holding timer(THT)

5. Explain about Ethernet.

_ Access method :CSMA/CD

_ Addressing

_ Electrical specification

_ Frame format

_ Implementation:

_ 10 base 5 :Thick Ethernet

_ 10 base 2 :Thin Ethernet

_ 10 base T :Twisted-pair Ethernet

_ 1 base 5 :Star LAN

6. Explain the frame format for token ring and token bus.

_ Access method: Token passing

_ Priority and reservation

_ Time limits

_ Monitor stations

7. Explain about HDLC.

_ Station types:

_ Primary station

_ Secondary station

_ Configurations:

_ Unbalanced configuration

_ Symmetrical configuration

_ Balanced configuration

_ Modes of communication:

_ Normal Response Mode(NRM)

_ Asynchronous Response Mode(ARM)

_ Asynchronous Balanced Mode(ABM)

_ Frames :

_ Flag field

_ Address field

_ Control field

_ Information field

_ FCS field


UNIT III

1. Explain the two approaches of packet switching techniques.

_ Datagram approach

_ Virtual circuit approach

_ Switched virtual circuit(SVC)

_ Permanent virtual circuit(PVC)

_ Circuit – switched connection versus virtual – circuit connection

_ Path versus route

_ Dedicated versus shared

2. Explain IP addressing method.

_ Internetwork protocol (IP)

_ Datagram

_ Addressing

_ Classes

_ Dotted decimal notation

_ A sample internet

3. Define routing & explain distance vector routing and link state routing.

_ Distance vector routing

_ Sharing information

_ Routing table

_ Creating the table

_ Updating the table

_ Updating algorithm

_ Link state routing

_ Information sharing

_ Packet cost

_ Link state packet

_ Getting information about neighbors

_ Initialization

_ Link state database

4. Define bridge and explain the type of bridges.

_ Bridges

_ Types of bridges

_ Simple bridge

_ Multiport bridge

_ Transparent bridge

5. Explain subnetting

_ Subnetting

_ Three levels of hierarchy

_ Masking

_ Masks without subnetting

_ Masks with subnetting

_ Finding the subnetwork address

_ Boundary level masking

_ Non-boundary level masking

6. Write short notes about repeaters, routers and gateways.

_ Repeaters

_ Routers

_ Routing concepts

_ Least-cost routing

_ Non adaptive routing

_ Adaptive routing

_ Packet lifetime

_ Gateways


UNIT IV

1. Explain the duties of transport layer.

End to end delivery

Addressing

Reliable delivery

Error control Sequence control Loss control Duplication control

Flow control

Multiplexing

2. Explain socket in detail.

Introduction Explanation program

3. Explain UDP & TCP.

_ User Datagram Protocol(UDP)

_ Source port address

_ Destination port address

_ Total length

_ Checksum

_ Transmission Control Protocol(TCP)

_ Source port address

_ Destination port address

_ Sequence number

_ Acknowledgement number

_ Header length

_ Reserved

_ Control

_ Window size

_ Check sum

_ Urgent pointer

_ Options and padding

4. Explain about congestion control.

_ Congestion avoidance

_ BECN

_ FECN

_ Four situations

_ Discarding

5. Explain leaky bucket and token bucket algorithm

_ Leaky bucket algorithm

_ Leaky bucket

_ Switch controlling the output rate

_ Flowchart


UNIT V

1. Explain the functions of SMTP.

System for sending messages to other computer users based on e-mail addresses. SMTP provides mail exchange between users on the same

or different computers.

User Agent

Mail Transfer Agent

Multipurpose Internet Mail Extensions

Post Office Protocol

2. Write short notes on FTP.

Transfer a file from one system to another. TCP connections

Basic model of FTP

3. Explain about HTTP.

HTTP transactions HTTP messages URL

4. Explain the WWW in detail.

Hypertext & Hypermedia Browser Architecture Categories of Web Documents HTML

CGI

Java

5. Explain the type of encryption/decryption method. Conventional Methods:

Character-Level Encryption: Substitutional & Transpositional

Bit-Level Encryption: Encoding/Decoding, Permutation, Substitution, Product, Exclusive-Or & Rotation

Public key Methods

6. Explain about RSA algorithm.

Public key Encryption technique. Encryption algorithm

Decryption algorithm

Security in RSA

7. Explain about secret key encryption algorithm. Data Encryption Standard

Algorithm

Sub key generation