CS2302 Computer Networks Two Marks Questions With Answers 2014

Anna University, Chennai

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UNIT I

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

_ 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

· 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