EC-603-A Data Communication - 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
   aWhat is Data communication? List and briefly describe the five main components of a data communication system.
   How to answer

   • Definition of data communication as exchange of data between devices
   • List five components: message, sender, receiver, transmission medium, protocol
   • Brief function of each component
2. 7 Marks
   bCalculate the time required to transmit 1024 bytes of data using serial transmission at 9600 bps. Compare this with the time required for parallel transmission assuming an 8-bit parallel channel with a clock rate of 1 MHz.
   How to answer

   • Total bits = 1024 bytes x 8 = 8192 bits
   • Serial time = total bits / 9600 bps calculation
   • Parallel time = total bytes / 1 MHz calculation
   • Comparison of serial vs parallel time
3. 7 Marks
   aExplain the concept of network topology. Briefly describe the following topologies: bus, star, ring and mesh.
   How to answer

   • Definition of network topology
   • Brief description of bus topology
   • Brief description of star, ring and mesh topologies
   • Advantages / use-cases comparison
4. 7 Marks
   bDraw the seven layers architecture of OSI model and describe the main function of each layer.
   How to answer

   • Neat diagram of 7-layer OSI model
   • List layers from Physical to Application
   • Main function of each layer in brief
5. 7 Marks
   aDescribe the various types of transmission impairments that can affect communication signals and what measures can be taken to mitigate these impairments.
   How to answer

   • Define attenuation, distortion, noise
   • Types of noise and other impairments
   • Effects on communication signals
   • Mitigation measures like shielding, amplification, equalization
6. 7 Marks
   bWhat is Message switching? How does it differ from packet switching? Discuss the advantages and disadvantages of message switching.
   How to answer

   • Definition of message switching with store-and-forward
   • Difference from packet switching on size, delay, routing
   • Advantages of message switching
   • Disadvantages of message switching
7. 7 Marks
   aDescribe the different methods of framing in data communication. How do these methods help in error detection and data integrity.
   How to answer

   • Definition of framing and its need
   • Methods: character count, byte stuffing, bit stuffing, physical layer coding
   • How framing delimits frames at receiver
   • Role in error detection and data integrity
8. 7 Marks
   bA message "1011001" needs to be transmitted using a Longitudinal Redundancy Check (LRC). Show how the LRC code is generated and how it helps in error detection.
   How to answer

   • Concept of LRC / parity per column
   • Steps to arrange message bits and compute LRC bit
   • LRC code for message 1011001
   • How receiver uses LRC to detect errors
9. 7 Marks
   aExplain the High-Level Data Link Control (HDLC) protocol. What are its main features and modes of operation?
   How to answer

   • HDLC frame structure: flag, address, control, information, FCS
   • Main features: bit-oriented, error control, flow control
   • Modes: NRM, ABM, ARM
   • Operation overview
10. 7 Marks
    bCompare and contrast Token Bus and Token Ring LAN architectures.
    How to answer

    • Basics of Token Bus and Token Ring access
    • Comparison on topology, medium, access method
    • Differences in performance and reliability
    • Summary table of contrast
11. 7 Marks
    aDiscuss the architecture and operation of the Distributed Queue Dual Bus (DQDB) protocol specified in the IEEE 802.6 standard. How does it support data transmission in a MAN?
    How to answer

    • DQDB dual-bus architecture per IEEE 802.6
    • Distributed queue mechanism and slots
    • Operation for data transmission
    • Support for MAN environment
12. 7 Marks
    bWhat is Asynchronous Transfer Mode (ATM)? Describe its cell-based architecture and switching mechanisms.
    How to answer

    • Definition of ATM as cell-switching technology
    • 53-byte cell structure: header and payload
    • Cell-based switching and virtual paths/channels
    • Advantages for voice-data-video integration
13. 7 Marks
    aDiscuss the roles and functions of repeaters, bridges, gateways and other networking devices in a computer network.
    How to answer

    • Function of repeaters at physical layer
    • Function of bridges, gateways, routers/switches
    • OSI layer of operation for each device
    • Role in interconnecting networks
14. 7 Marks
    bDefine link state routing. How does it differ from distance vector routing in terms of routing table updates and route calculation?
    How to answer

    • Definition of link state routing
    • Routing table update and flooding of link state
    • Route calculation using Dijkstra
    • Differences from distance vector routing
15. 14 Marks
    Write a short note on any two :

    1. a)Line Encoding
    2. b)Stop and Wait Protocol
    3. c)FDDI
    4. d)Overview of TCP/IP
    How to answer

    • Select any two topics from list
    • Key concept, working and diagram for each
    • Advantages / applications
    • Concise structured short note