(SEM VI) THEORY EXAMINATION 2023-24 COMPUTER NETWORKS

KCS603 – COMPUTER NETWORKS (B.Tech Sem VI, 2023–24)

All answers are written in simple, clear, humanized language (not short bullet points) and are prepared strictly according to your uploaded question paper.
Reference: Uploaded Question Paper 

KCS603-COMPUTER-NETWORKS

SECTION A

Attempt all questions in brief (2 × 10 = 20 marks)

(a) Applications of Computer Networks

Computer networks are used for communication through emails, video calls, and messaging. They support resource sharing such as printers and files, enable online banking and e-commerce, provide access to cloud services, and support distributed computing and social networking.

(b) Advantages and disadvantages of Mesh Topology

In mesh topology, every node is connected to every other node. This provides high reliability, fault tolerance, and security because multiple paths exist between nodes. However, it is expensive, complex to install, and difficult to maintain due to large number of connections.

(c) Fixed and variable size framing

In fixed size framing, frames have a constant size and the receiver knows frame boundaries in advance. In variable size framing, frames have different sizes and special delimiters or length fields are used to identify frame boundaries.

(d) Working of a Bridge

A bridge operates at the data link layer and connects two or more LAN segments. It examines MAC addresses of incoming frames and forwards them only to the required segment, reducing traffic and collisions.

(e) Delivery in Network Layer

Delivery refers to the process of transporting packets from the source host to the destination host across multiple networks. The network layer ensures logical addressing and routing for correct delivery.

(f) Token Bucket

Token Bucket is a traffic shaping algorithm that controls the rate of data transmission. Tokens are generated at a fixed rate and stored in a bucket. Data can be sent only if sufficient tokens are available, allowing controlled bursts.

(g) Registered ports

Registered ports range from 1024 to 49151. They are assigned by IANA for specific applications such as HTTP (8080), MySQL (3306), and FTP control (21 in practice, though well-known).

(h) Connectionless vs connection-oriented

Connectionless communication sends data without establishing a connection and does not guarantee delivery, such as UDP. Connection-oriented communication establishes a connection first and ensures reliable delivery, such as TCP.

(i) Telnet

Telnet is a remote login protocol that allows a user to access another computer over a network. It operates on port 23 but is insecure because data is transmitted in plain text.

(j) Compression

Compression is the process of reducing the size of data to save storage space and transmission time. It can be lossless or lossy depending on whether original data can be perfectly reconstructed.

SECTION B

Attempt any three (3 × 10 = 30 marks)

(a) TCP/IP Model in detail

The TCP/IP model consists of four layers.
The Application layer provides services like HTTP, FTP, SMTP, and DNS.
The Transport layer ensures end-to-end communication using TCP (reliable) and UDP (unreliable).
The Internet layer handles logical addressing and routing using IP, ICMP, and ARP.
The Network Access layer deals with physical transmission and framing using Ethernet and other protocols.

(b) Noisy Channel Protocols

Noisy channel protocols handle errors during data transmission.
Stop-and-Wait ARQ sends one frame and waits for acknowledgment.
Go-Back-N ARQ allows multiple frames but retransmits all frames after an error.
Selective Repeat ARQ retransmits only the erroneous frames, improving efficiency.
(Diagram showing sender, receiver, ACKs, and retransmissions is drawn in exam.)

(c) IPv4 Header Format

The IPv4 header contains fields such as version, header length, type of service, total length, identification, flags, fragment offset, TTL, protocol, checksum, source IP, and destination IP. These fields help in routing, fragmentation, and error control.

(d) TCP features and header

TCP provides reliable, ordered, and error-free delivery. Features include flow control, congestion control, and full-duplex communication.
The TCP header includes source port, destination port, sequence number, acknowledgment number, header length, flags, window size, checksum, and urgent pointer.

(e) SNMP

SNMP (Simple Network Management Protocol) is used to monitor and manage network devices. It consists of manager, agent, MIB, and uses operations like GET, SET, and TRAP. SNMP works mainly over UDP.

SECTION C

Attempt any one (1 × 10 = 10 marks)

(a) Network Devices at each OSI Layer

Physical layer uses hubs and repeaters.
Data link layer uses bridges and switches.
Network layer uses routers.
Transport layer uses gateways.
Application layer uses proxies and application gateways.
Each device operates at its respective layer to provide specific functionality.

(b) Network topologies with features, pros, and cons

Bus, star, ring, mesh, and tree topologies define network structure.
Star topology is easy to manage but depends on central hub.
Ring topology provides equal access but failure affects entire network.
Mesh topology is reliable but costly.
Neat diagrams are expected in exam.