AD-602 Computer Networks - Jun 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aCompare and contrast the OSI and TCP/IP reference models in detail. Which model is more relevant in today's networking environment and why?
   How to answer

   • Layers and functions of OSI 7-layer model vs TCP/IP 4-layer model
   • Comparison table: services, protocols, layering, header, approach
   • Usage and practical relevance today
   • Conclusion why TCP/IP is more relevant with examples
2. 7 Marks
   bClassify computer networks. Discuss the significance of service primitives in connection-oriented and connectionless services.
   How to answer

   • Classification: PAN, LAN, MAN, WAN by scale and others
   • Connection-oriented vs connectionless service concepts
   • Service primitives: LISTEN, CONNECT, SEND, RECEIVE, DISCONNECT
   • Significance with examples
3. 7 Marks
   aA company is designing a network using different topologies. The network consists of 20 nodes, and the cost of establishing a link between two nodes is $100 per connection. Calculate the total number of links and the total cost for the following topologies: Also, analyze which topology is most cost-effective and which provides the highest redundancy.

   1. i)Bus Topology
   2. ii)Ring Topology
   3. iii)Star Topology
   4. iv)Mesh Topology
   How to answer

   • Formulas for links: Bus N-1, Ring N, Star N, Mesh N(N-1)/2
   • Calculate number of links for N=20
   • Calculate total cost at $100 per link
   • Compare cost-effectiveness vs redundancy
4. 7 Marks
   bDescribe and compare Go-Back-N and Selective Repeat Sliding Window protocols.
   How to answer

   • Working of Go-Back-N with window and cumulative ACK
   • Working of Selective Repeat with individual ACK and buffering
   • Comparison on efficiency, complexity, bandwidth
   • Use cases and examples
5. 7 Marks
   aWhat do you mean by Distributed Random Access Scheme? Compare and analyze the working principle of Pure and Slotted ALOHA protocols.
   How to answer

   • Meaning of distributed random access scheme
   • Pure ALOHA working, vulnerable time and efficiency 18.4%
   • Slotted ALOHA working, efficiency 36.8%
   • Comparison and analysis
6. 7 Marks
   bExplain the working of CSMA/CD protocol. A network using CSMA/CD has a bandwidth of 10 Mbps. If the maximum propagation time (including the delays in the devices and ignoring the time needed to send a jamming signal) is $25.6\, \mu s$, what is the minimum size of the frame?
   How to answer

   • CSMA/CD steps: carrier sense, collision detection, backoff
   • Condition minimum frame transmission time >= 2*propagation time
   • Calculate frame size = bandwidth * 2*Tp
   • Result in bits and bytes
7. 7 Marks
   aExplain the concept of hierarchical routing. What are its benefits and limitations compared to flat routing?
   How to answer

   • Concept of hierarchical vs flat routing
   • Benefits: scalability, reduced table size
   • Limitations: suboptimal paths, complexity
   • Example of two-level hierarchy
8. 7 Marks
   bA network consists of 6 nodes (A, B, C, D, E, F) with given link costs. Using Dijkstra's algorithm, determine the shortest path from node A to all other nodes.
   How to answer

   • Initialize distances from source A, visited set
   • Iterative relaxation steps in tabular form
   • Final shortest distances and predecessor
   • Shortest paths from A to B, C, D, E, F
9. 7 Marks
   aDescribe the process of packet fragmentation and reassembly in IPv4. How does IPv6 handle fragmentation differently?
   How to answer

   • IPv4 fragmentation fields: MF, DF, offset, MTU
   • Reassembly at destination process
   • IPv6: only source fragments, extension header
   • Comparison of differences
10. 7 Marks
    bExplain the process of TCP connection establishment and termination using the three-way and four-way handshake mechanisms. Why is it necessary to have a graceful termination process?
    How to answer

    • Three-way handshake: SYN, SYN-ACK, ACK steps
    • Four-way termination: FIN, ACK sequence
    • State diagram explanation
    • Need for graceful termination to avoid data loss
11. 7 Marks
    aCompare the working of TCP and UDP in terms of reliability, speed and use cases, Provide examples of applications that use each protocol.
    How to answer

    • TCP features: reliable, connection-oriented, examples
    • UDP features: unreliable, fast, low overhead, examples
    • Comparison table on reliability, speed, use cases
    • Applications: HTTP, FTP vs DNS, VoIP, video
12. 7 Marks
    bDiscuss the impact of TCP congestion control mechanism such as Slow Start, Congestion Avoidance, and Fast Retransmit on network performance.
    How to answer

    • Slow Start exponential growth and ssthresh
    • Congestion Avoidance AIMD behavior
    • Fast Retransmit on triple duplicate ACK
    • Overall impact on throughput and stability
13. 7 Marks
    aExplain the following application layer protocols:

    1. i)HTTP
    2. ii)DNS
    How to answer

    • HTTP: request-response, methods, stateless
    • DNS: hierarchical resolution, records
    • Port numbers and application use
    • Example exchanges
14. 7 Marks
    bExplain the differences between symmetric and asymmetric encryption techniques. How do modern ciphers improve network security compared to traditional ciphers?
    How to answer

    • Symmetric: single key, fast, key distribution issue
    • Asymmetric: public-private key, slower, secure exchange
    • Comparison table
    • Modern vs traditional ciphers improvement
15. 14 Marks
    Write a short note on (any two)

    1. a)SMTP, MIME and IMAP email protocols
    2. b)Bellman-ford algorithm
    3. c)IEEE Standards 802 series
    4. d)Types of transmission media (guided and unguided)
    How to answer

    • Select any two topics with definition and purpose
    • Working principles and key features/diagrams
    • Advantages, limitations and applications
    • Concluding summary