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computer network part B

PART B

UNIT I

Data communications

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

Data link layer

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

UNIT III

Network layer

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

UNIT IV

Transport layer

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

Application Layer

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

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