CY-403 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
   aExplain the ISO-OSI reference model in detail. Compare it with the TCP/IP model based on layer functionalities and real-world implementation.
   How to answer

   • Describe 7 layers of ISO-OSI with functions
   • Describe 4-layer TCP/IP model
   • Compare layer functionalities in table
   • Compare real-world implementation and usage
2. 7 Marks
   bIf a noiseless channel has a bandwidth of 3 kHz and each signal level carries 4 bits, calculate the maximum bit rate using the Nyquist formula. What if the number of signal levels in increased?
   How to answer

   • State Nyquist formula: Bit rate = 2*B*log2(L)
   • Substitute B=3 kHz, bits per level=4
   • Calculate maximum bit rate
   • Explain effect of increasing signal levels
3. 7 Marks
   aExplain the principles and operation of circuit switching, packet switching and message switching.
   How to answer

   • Define circuit switching with phases
   • Define packet switching and datagram vs virtual circuit
   • Define message switching
   • Compare principles and operation
4. 7 Marks
   bGiven a data block : 1101011011 and generator polynomial : 10011. Perform CRC computation and provide the final codeword.
   How to answer

   • Append 4 zero bits to data block
   • Perform binary division by 10011
   • Obtain CRC remainder
   • Form final codeword: data + remainder
5. 7 Marks
   aExplain the stop-and-wait protocol and sliding window protocol. How does the sender and receiver manage buffers in both cases?
   How to answer

   • Explain stop-and-wait operation with ACK and timers
   • Explain sliding window with send/receive windows
   • Compare sender buffer management
   • Compare receiver buffer management
6. 7 Marks
   bDiscuss static Vs dynamic channel allocation. Compare ALOHA, slotted ALOHA and CSMA protocols.
   How to answer

   • Define static vs dynamic channel allocation
   • Explain ALOHA throughput and vulnerability
   • Explain slotted ALOHA improvement
   • Explain CSMA variants and comparison
7. 7 Marks
   aDescribe IEEE 802.3, IEEE 802.4 and IEEE 802.5 LAN standards in terms of access methods, performance and topology.
   How to answer

   • Describe IEEE 802.3 CSMA/CD access method
   • Describe IEEE 802.4 token bus access method
   • Describe IEEE 802.5 token ring access method
   • Compare performance and topology
8. 7 Marks
   bCompare and contrast the operations of hubs, switches, bridges, routers and gateways.
   How to answer

   • Define function and layer of hub, switch, bridge
   • Define function and layer of router, gateway
   • Compare operations in table
   • Contrast collision/broadcast domain handling
9. 7 Marks
   aExplain remote bridging. What challenges arise in implementing remote bridges in large LANs?
   How to answer

   • Define remote bridging concept
   • Explain implementation in large LANs
   • List challenges: latency, loops, scalability
   • Suggest handling of challenges
10. 7 Marks
    bCompare connection establishment and release in TCP using three-way and four-way handshakes. Why is graceful termination important?
    How to answer

    • Explain TCP three-way handshake for establishment
    • Explain four-way handshake for release
    • Explain graceful termination need
    • Compare establishment vs release steps
11. 7 Marks
    aDiscuss the working of link state routing and distance vector routing algorithms with their convergence speed and scalability.
    How to answer

    • Explain link state routing with Dijkstra
    • Explain distance vector with Bellman-Ford
    • Compare convergence speed
    • Compare scalability
12. 7 Marks
    bDescribe classful IP addressing. Discuss the limitations that led to the evolution of CIDR and classless addressing.
    How to answer

    • Define classful IP classes A-E
    • List limitations: wastage, exhaustion
    • Explain CIDR and classless concept
    • Explain benefits of CIDR
13. 7 Marks
    aYou are given a network 192.168.10.0/24. Divide it into 4 subnets and determine the range of IP addresses and broadcast address for each subnet.
    How to answer

    • Borrow 2 bits for 4 subnets (/26)
    • Calculate subnet addresses and masks
    • Determine usable IP range per subnet
    • Determine broadcast address per subnet
14. 7 Marks
    bDescribe the working of DNS. How does it resolve domain names to IP addresses using caching and hierarchical servers.
    How to answer

    • Define DNS purpose and hierarchy
    • Explain iterative vs recursive resolution
    • Explain caching role
    • Explain hierarchical servers: root, TLD, authoritative
15. 14 Marks
    Write a short note on (any two) :

    1. a)ARP, RARP and ICMP protocols
    2. b)PPP, SLIP and HDLC protocols
    3. c)Types of transmission media (guided and unguided)
    How to answer

    • Select any two topics from a,b,c
    • Give definition and purpose for each
    • Explain operation with example/diagram
    • Compare variants where applicable