AL-602 Computer Networks - May 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

   • Definition of ISO-OSI 7-layer reference model
   • List and function of each layer from Physical to Application
   • Data flow / encapsulation through layers
   • Neat labelled diagram of 7 layers
2. 7 Marks
   bExplain connectionless and connection oriented services. Give examples of each.
   How to answer

   • Definition of connectionless service
   • Definition of connection-oriented service
   • Key differences and characteristics
   • Examples of each e.g. UDP/IP vs TCP
3. 7 Marks
   aWith a neat diagram explain in detail about the Network architecture.
   How to answer

   • Definition of network architecture
   • Client-server / layered architecture components
   • Functions of layers / entities
   • Neat labelled diagram
4. 7 Marks
   bDistinguish between peer-to-peer relationship and a primary-secondary relationship.
   How to answer

   • Definition of peer-to-peer relationship
   • Definition of primary-secondary relationship
   • Control / authority differences
   • Examples and applications
5. 7 Marks
   aExplain TCP/IP Model.
   How to answer

   • Origin and purpose of TCP/IP model
   • Description of 4/5 layers and functions
   • Protocols at each layer
   • Comparison with OSI in brief
6. 7 Marks
   bExplain the frame format, operation and ring maintenance feature of IEEE 802.5 MAC protocol.
   How to answer

   • IEEE 802.5 token ring frame fields
   • Token passing operation
   • Ring maintenance functions e.g. monitor station
   • Diagram of frame / ring
7. 7 Marks
   aExplain the various error detection and correction mechanisms used in computer network.
   How to answer

   • Concept of redundancy for error control
   • Error detection: parity, CRC, checksum
   • Error correction: Hamming code, ARQ
   • Comparison of efficiency / application
8. 7 Marks
   bDescribe sliding window protocol using Go back n.
   How to answer

   • Principle of sliding window flow control
   • Go-Back-N sender and receiver windows
   • Retransmission on timeout / cumulative ACK
   • Example / diagram of window movement
9. 7 Marks
   aExplain distributed random access schemes/contention schemes for data services.
   How to answer

   • Need for distributed contention access
   • ALOHA / Slotted ALOHA operation
   • CSMA / CSMA-CD / CSMA-CA schemes
   • Applications to data services
10. 7 Marks
    bExplain MAC sub layer protocol and frame structure of IEEE 802.11.
    How to answer

    • IEEE 802.11 MAC functions and access modes
    • CSMA/CA, DCF / PCF operation
    • 802.11 frame structure and fields
    • Control / management / data frame types
11. 7 Marks
    aCompare IPv4 and IPv6.
    How to answer

    • Address size: 32-bit vs 128-bit
    • Header format and extension headers
    • Addressing, security and QoS features
    • Tabular comparison summary
12. 7 Marks
    bExplain Dijkstra's algorithm for routing. Discuss its limitations.
    How to answer

    • Dijkstra shortest-path steps for routing
    • Link-state application with example
    • Limitations e.g. scalability, convergence, overhead
    • Conclusion on use in OSPF/IS-IS
13. 14 Marks
    An ISP is granted a block of addresses starting with $190.100.0.0/16$ ($65,536$ addresses). The ISP needs to distribute these addresses to three groups of customers as follows: Design the sub-blocks and find out how many addresses are still available after these allocations?

    1. a)The first group has 64 customers; each needs 256 addresses.
    2. b)The second group has 128 customers; each needs 128 addresses.
    3. c)The third group has 128 customers; each needs 64 addresses.
    How to answer

    • Calculate total addresses and prefix for each group (/24, /25, /26)
    • Allocate sub-blocks sequentially from 190.100.0.0/16
    • List first and last address of each sub-block
    • Compute used vs still available addresses
14. 14 Marks
    Write brief notes:

    1. i)SMTP
    2. ii)Congestion Control
    3. iii)DNS
    4. iv)SNMP
    How to answer

    • SMTP role, commands and mail transfer steps
    • Congestion control causes and algorithms
    • DNS hierarchy and resolution process
    • SNMP architecture and management functions