IT-502 Computer Networks - Dec 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
   aDefine Local Area Network (LAN) and Wide Area Network (WAN). Compare LAN and WAN in terms of coverage area, transmission speed and applications.
   How to answer

   • Define LAN as network confined to small area like office/building/campus
   • Define WAN as network spanning large geographical area using leased/telecom links
   • Compare on coverage area, ownership, transmission speed, delay, error rate
   • Compare on applications with examples
2. 7 Marks
   bExplain the ISO-OSI reference model in detail. Describe the functions of each of the seven layers.
   How to answer

   • State ISO-OSI as 7-layer reference model for open interconnection
   • List seven layers from Physical to Application
   • Explain function of each layer in order
   • Mention encapsulation, peer-to-peer communication and data flow
3. 7 Marks
   aDescribe the TCP/IP reference model. Compare the TCP/IP model with the ISO-OSI model.
   How to answer

   • Describe 4-layer TCP/IP model: Network Access, Internet, Transport, Application
   • Explain role of each layer and key protocols
   • Compare TCP/IP vs OSI on layers, services, protocols, development approach
   • Give mapping diagram between models
4. 7 Marks
   bExplain Address Resolution Protocol (ARP). Discuss its packet formats.
   How to answer

   • Define ARP purpose: mapping IP address to MAC address
   • Explain ARP request/reply broadcast and caching operation
   • Describe ARP packet fields and sizes
   • Mention RARP/inverse ARP and limitations
5. 7 Marks
   aExplain flow control and error control mechanisms in the Data Link Layer.
   How to answer

   • Define flow control need to match sender-receiver rates
   • Define error control need for detection and retransmission
   • Explain mechanisms: feedback, timers, sequence numbers, ACK/NAK
   • Mention stop-and-wait and sliding window as examples
6. 7 Marks
   bDescribe the Stop-and-Wait protocol in detail. Explain its working with a suitable diagram.
   How to answer

   • Describe Stop-and-Wait principle with one frame at a time and ACK
   • Explain sender and receiver algorithm with timers and sequence numbers 0/1
   • Illustrate normal, lost frame, lost ACK and delayed cases with timeline diagram
   • Mention efficiency and utilization limitation
7. 7 Marks
   aExplain the HDLC (High-Level Data Link Control) protocol. Describe its frame format.
   How to answer

   • Define HDLC as bit-oriented data link protocol
   • Explain modes: NRM, ABM, ARM and frame types I, S, U
   • Describe frame format fields: flag, address, control, information, FCS, flag
   • Mention bit stuffing and access procedures
8. 7 Marks
   bDescribe the functions of Logical Link Control (LLC) and Media Access Control (MAC) sublayers.
   How to answer

   • State LLC and MAC as Data Link sublayers per IEEE 802
   • Explain LLC functions: multiplexing, flow/error control, SAP
   • Explain MAC functions: framing, addressing, channel access, collision handling
   • Compare roles with examples like CSMA/CD, token passing
9. 7 Marks
   aExplain the Internet Protocol (IP) in detail. Describe the IPv4 header format.
   How to answer

   • Define IP as connectionless network layer protocol for routing
   • Explain addressing, fragmentation, routing functions
   • Describe IPv4 header fields and their sizes
   • Mention services and header diagram
10. 7 Marks
    bWhat is Transmission Control Protocol (TCP)? Explain TCP header format.
    How to answer

    • Define TCP as connection-oriented reliable transport protocol
    • Explain services: stream delivery, reliability, flow and congestion control
    • Describe TCP header fields: ports, sequence, ACK, flags, window, checksum
    • Mention connection establishment and header diagram
11. 7 Marks
    aExplain the Transport Layer in detail. How process-to-process delivery is achieved in computer networks?
    How to answer

    • Define transport layer role and end-to-end delivery
    • Explain addressing with port numbers and socket
    • Explain segmentation, reassembly, connection control, multiplexing
    • Explain how process-to-process delivery uses port addressing and encapsulation
12. 7 Marks
    bExplain the concept of Quality of Service (QoS) in the transport layer.
    How to answer

    • Define QoS as set of performance requirements for data flow
    • Explain parameters: bandwidth, delay, jitter, loss, reliability
    • Explain QoS mechanisms at transport layer: buffering, scheduling, traffic shaping
    • Give examples of applications needing QoS
13. 7 Marks
    aExplain User Datagram Protocol (UDP) in detail.
    How to answer

    • Define UDP as connectionless unreliable transport protocol
    • Explain header fields: source/dest port, length, checksum
    • Explain use cases: DNS, streaming, VoIP where speed matters
    • Compare briefly with TCP
14. 7 Marks
    bExplain the E-Mal system architecture. Describe the working principles of SMTP protocol.
    How to answer

    • Describe E-mail architecture: UA, MTA, MAA, mail servers and protocols
    • Explain SMTP working: commands, responses, mail transfer phases
    • Illustrate end-to-end mail flow with POP3/IMAP role
    • Mention ports and example session
15. 7 Marks
    aExplain Simple Network Management Protocol (SNMP). Discuss its components.
    How to answer

    • Define SNMP for managing network devices
    • Explain components: manager, agent, MIB, SMI
    • Explain operations: Get, Set, Trap and message flow
    • Mention SNMP versions and UDP ports
16. 7 Marks
    bAn organization is assigned the IP address 172.16.5.25. Answer the following :

    1. (i))Identify the class of the IP address.
    2. (ii))Find the default subnet mask.
    3. (iii))Determine the network ID and host ID.
    4. (iv))Find the broadcast address.
    How to answer

    • Identify Class B from first octet 172 in 128-191 range
    • Write default mask 255.255.0.0 and /16 prefix
    • Derive network ID 172.16.0.0 and host ID 0.0.5.25
    • Derive broadcast address 172.16.255.255