AL-602 Computer Networks - Dec 2024 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 model of computer network with a neat diagram.
   How to answer

   • Define 7 layers of ISO-OSI model in order
   • Explain function of each layer briefly
   • Draw neat labelled diagram showing layers, data flow and headers
   • Mention OSI vs TCP/IP relevance
2. 7 Marks
   bExplain the Finite state machine models and Petri Net models.
   How to answer

   • Define Finite State Machine model for protocols
   • Define Petri Net model with places, transitions, tokens
   • Explain use in protocol specification and verification
   • Give simple example of each
3. 7 Marks
   aWith a neat diagram explain in detail about the Network architecture.
   How to answer

   • Define network architecture (layered, TCP/IP)
   • Explain layers and their functions
   • Draw neat labelled diagram of architecture
   • Mention protocols at each layer
4. 7 Marks
   bExplain Data Link address with examples.
   How to answer

   • Define Data Link address / MAC address
   • Explain format e.g., 48-bit hexadecimal
   • Explain uniqueness and flat addressing
   • Give examples of MAC addresses
5. 7 Marks
   aExplain connection establishment and connection release in transport protocols.
   How to answer

   • Define connection establishment in transport layer (three-way handshake)
   • Explain connection release (graceful / abrupt)
   • Describe timers, sequence numbers and states
   • Explain connection-oriented vs connectionless context
6. 7 Marks
   bA channel has a bit rate of 4 kbps and propagation delay of 20 msec. For what range of frame size does stop and wait protocol gives an efficiency of at least 50%?
   How to answer

   • Recall stop-and-wait efficiency formula eta = Tt/(Tt+2Tp)
   • Substitute bit rate 4 kbps and propagation delay 20 msec
   • Solve for frame size L for eta >= 0.5
   • State range L >= 160 bits
7. 7 Marks
   aExplain the various error detection and correction mechanisms used in computer network.
   How to answer

   • Define single-bit, burst errors
   • Explain parity, CRC, checksum for detection
   • Explain Hamming code, FEC for correction
   • Compare detection vs correction with examples
8. 7 Marks
   bDescribe sliding window protocol using Go back n.
   How to answer

   • Define sliding window concept with sender/receiver windows
   • Explain Go-Back-N operation, window size, timers
   • Describe retransmission on timeout/error
   • Give example sequence and efficiency
9. 7 Marks
   aWhat is Congestion control and how it is implemented in network layer?
   How to answer

   • Define congestion and its causes/effects
   • Explain open-loop vs closed-loop control
   • Explain implementation in network layer (leaky bucket, RED, choke packets)
   • Mention routing and traffic shaping role
10. 7 Marks
    bExplain MAC sub layer protocol and frame structure of IEEE 802.11.
    How to answer

    • Define MAC sublayer role in IEEE 802.11
    • Explain CSMA/CA, DCF/PCF access methods
    • Describe 802.11 frame structure and fields
    • Draw frame format diagram
11. 7 Marks
    aCompare IPv4 and IPv6.
    How to answer

    • Compare address size 32-bit vs 128-bit
    • Compare header format, checksum, fragmentation
    • Compare security, QoS, auto-configuration
    • Summarize in table
12. 7 Marks
    bExplain Least cost routing algorithm. Discuss its limitations.
    How to answer

    • Define least-cost / shortest-path routing (Dijkstra)
    • Explain algorithm steps with example
    • Discuss count-to-infinity, scalability, overhead limitations
    • Mention link-state vs distance-vector context
13. 7 Marks
    aDiscuss the concept of TCP flow control and TCP congestion control.
    How to answer

    • Define TCP flow control using sliding window, rwnd
    • Define TCP congestion control: slow start, AIMD, fast retransmit
    • Differentiate flow vs congestion control
    • Explain cwnd vs rwnd interaction
14. 7 Marks
    bExplain transport layer multiplexing and demultiplexing.
    How to answer

    • Define multiplexing/demultiplexing using ports/sockets
    • Explain how sender multiplexes and receiver demultiplexes
    • Give example with UDP/TCP port numbers
    • Mention connectionless vs connection-oriented demux
15. 14 Marks
    Write short notes:

    1. i)IMAP
    2. ii)UDP
    3. iii)DNS
    4. iv)MIME
    How to answer

    • Define IMAP purpose and features
    • Define UDP header and use cases
    • Define DNS hierarchy and resolution
    • Define MIME types for multimedia mail