About this previous year paper
Computer Networks (NCS-601)
Complete Section-Wise Explanation – B.Tech Semester VI
Introduction to the Subject
Computer Networks is one of the most important core subjects in computer science and IT because it explains how computers communicate with each other, how data travels from one system to another, and how the internet actually works behind the scenes.
This subject helps students understand: Network architectures and models
Data transmission techniques Error and congestion control
TCP/IP and OSI models Routing, addressing, and transport protocols
Application-layer services like HTTP, FTP, DNS, and SNMP
The question paper is divided into three sections: A, B, and C, and all sections must be attempted as per the instructions.
SECTION A – Basic Concepts & Numerical Understanding
Pattern:
Attempt all questions
10 questions × 2 marks = 20 marks
Nature of Section A
Section A checks whether your fundamental concepts are clear. The answers should be short, direct, and accurate. Many questions also test numerical understanding, so formulas must be remembered clearly.
Explanation of Section A Topics
Applications of Computer Networks
Computer networks are used for resource sharing, communication (email, video calls), information sharing, e-commerce, online banking, cloud computing, and distributed systems.
Ring Topology: Advantages and Disadvantages
In ring topology, each node is connected in a circular manner. It avoids collisions and provides equal access, but failure of one node or cable can disrupt the entire network.
Count-to-Infinity Problem
This problem occurs in distance vector routing protocols when routers continuously update incorrect routing information, causing routing loops and slow convergence.
Subnet Address Calculation
This question tests understanding of subnetting. Using the given IP address and subnet mask, the subnet address is calculated by applying bitwise AND operation.
Piggybacking
Piggybacking is a technique in which acknowledgment is sent along with data frames instead of sending a separate ACK frame, improving efficiency.
Slotted ALOHA Performance
This numerical checks understanding of channel load and throughput in slotted ALOHA. Knowing the throughput formula is essential.
Causes of Network Congestion
Congestion occurs due to high traffic load, insufficient bandwidth, slow routers, buffer overflow, and retransmissions.
Duplication Control by Transport Layer
The transport layer uses sequence numbers to identify duplicate packets and ensures that each packet is delivered only once.
Maximum Data Rate (Shannon Capacity)
This numerical uses Shannon’s formula to calculate maximum achievable data rate based on bandwidth and signal-to-noise ratio.
Use of HTTP
HTTP is an application-layer protocol used for transferring web pages between a client (browser) and a server.
SECTION B – Conceptual Explanation & Protocols
Pattern:
Attempt any three questions
3 × 10 marks = 30 marks
Nature of Section B
Section B requires well-explained descriptive answers. You must write in paragraph form, include diagrams where necessary, and explain advantages, disadvantages, and working principles clearly.
Explanation of Important Questions
Network Topologies
This question requires explanation of bus, star, ring, mesh, and hybrid topologies. You must describe their structure, working, advantages, disadvantages, and suitable applications. Diagrams significantly improve answer quality.
Data Link Layer Issues and Protocols
The data link layer deals with framing, error control, flow control, and access control. Protocols are designed based on layering principles to ensure reliable data transfer between adjacent nodes.
Congestion and Its Prevention Techniques
Congestion is a condition where network performance degrades due to excessive traffic. Prevention techniques include traffic shaping, admission control, and congestion-aware routing.
TCP Header and Working of TCP
This question tests understanding of TCP structure and reliability. You must explain TCP header fields, working of TCP, and then clearly differentiate TCP and UDP in terms of reliability, connection orientation, and use cases.
TELNET and Its Working
TELNET is a remote login protocol that allows users to access a remote system as if they were locally connected. The working procedure involves client-server communication over TCP.
SECTION C – Long Answer & Core Architecture
Pattern:
Attempt any one part from each question
5 questions × 10 marks = 50 marks
This section has the highest weightage and plays a major role in final scoring. Answers must be
structured, detailed, and conceptually strong.
Question 3
OSI Model
This question is very important. You must explain all seven layers, their functions, services, and protocols. A neat layered diagram is highly recommended.
Physical Layer Transmission Media
This includes guided media (twisted pair, coaxial cable, optical fiber) and unguided media (radio waves, microwaves, infrared). Explanation should include characteristics and applications.
Question 4
Carrier Sense Protocols
Carrier sense protocols like CSMA/CD and CSMA/CA reduce collisions by sensing the channel before transmission. You must compare them with collision-based protocols.
ARQ Protocols
Stop-and-Wait ARQ, Sliding Window Protocol, and Go-Back-N ARQ are explained with working principles, diagrams, and efficiency comparison.
Question 5
IP Addressing and Subnetting
This question tests understanding of IP address classes, subnetting process, and benefits of subnetting. Numerical examples strengthen the answer.
Unicast Routing Protocols
Unicast routing delivers packets from one sender to one receiver. Protocols like RIP, OSPF, and BGP are explained with their working and features.
Question 6
Transport Layer Reliability
This question explains how transport layer ensures reliable delivery using sequencing, acknowledgments, flow control, and error control.
Three-Way Handshaking
This is a must-prepare topic. You must explain SYN, SYN-ACK, and ACK steps clearly with a connection-establishment diagram.
Question 7
Application Layer Protocols
DNS translates domain names into IP addresses.
VoIP enables voice communication over the internet.
FTP is used for file transfer between systems.
SNMP Protocol
SNMP is used for network management. Explanation includes manager, agent, MIB, and operations like GET, SET, and TRAP.