IT-502 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
   aCompare and contrast the delays in connectionless and connection-oriented services. Which service creates less delay if the message is large? Which service creates less delay if the message is small?
   How to answer

   • Define connectionless vs connection-oriented service
   • Compare setup, per-packet routing, reliability and delay components
   • Analyze large message: segmentation and pipeline vs setup overhead
   • Conclude which service has less delay for large vs small messages
2. 7 Marks
   bExplain the purpose of ARP protocol. Why is ARP request broadcast but ARP reply unicast?
   How to answer

   • Define ARP and its role in IP to MAC resolution
   • Explain ARP request broadcast procedure
   • Explain ARP reply unicast to requester and caching
   • Reason: unknown location vs known location
3. 7 Marks
   aA bit stream 10011101 is transmitted using the standard CRC method described in the text. The generator polynomial is $x^3 + 1$. Show the actual bit string transmitted. Suppose the third bit from the left is inverted during transmission. Show that this error is detected at the receiver's end.
   How to answer

   • State generator $x^3+1$ i.e. divisor 1001 and 3 CRC bits
   • Show binary division of 10011101 appended with 000 to get remainder
   • Write transmitted codeword: data + remainder
   • Divide corrupted received word by 1001 to show non-zero remainder hence error detected
4. 7 Marks
   bExplain the working of carrier sense multiple access protocol.
   How to answer

   • Define CSMA and carrier sensing principle
   • Explain persistence / non-persistence and backoff
   • Explain collision detection/avoidance working steps
   • State advantages and limitations
5. 7 Marks
   aExplain various error reporting messages in ICMP protocol.
   How to answer

   • Define ICMP role in error reporting
   • List error messages: destination unreachable, time exceeded, parameter problem, source quench, redirect
   • Explain format and when each is generated
   • Note query vs error message distinction
6. 7 Marks
   bFind the netid and the hostid of the following IP addresses:

   1. i)114.34.2.8
   2. ii)132.56.8.6
   3. iii)208.34.54.12
   4. iv)251.34.98.5
   How to answer

   • Recall class A/B/C/D/E ranges from first octet
   • Identify class and default netid/hostid split for each address
   • Extract netid and hostid for 114.34.2.8, 132.56.8.6, 208.34.54.12, 251.34.98.5
   • Present results in tabular form
7. 7 Marks
   aExplain how the TCP connection can be establish and release?
   How to answer

   • Define TCP as connection-oriented reliable protocol
   • Explain three-way handshake for establishment with SYN, SYN-ACK, ACK
   • Explain graceful release with FIN, ACK and states
   • Include connection state diagram / segment exchange
8. 7 Marks
   bExplain the principles behind:

   1. i)The SACK-permitted option,
   2. ii)How protection against wrapped sequence numbers can be overcome by using the time-stamp option.
   How to answer

   • Define SACK-permitted option and selective acknowledgment need
   • Explain how SACK blocks identify non-contiguous received data
   • Define PAWS and time-stamp option fields
   • Show how timestamps distinguish wrapped sequence numbers
9. 7 Marks
   aExplain about the principle of HTTP operation.
   How to answer

   • Define HTTP as application-layer request-response protocol
   • Explain client-server operation, URL, methods and status codes
   • Explain persistent vs non-persistent connections
   • Give example transaction steps
10. 7 Marks
    bExplain about remote login in detail.
    How to answer

    • Define remote login and TELNET concept
    • Explain NVT, negotiation and terminal emulation
    • Explain steps of establishing remote session
    • State uses and security considerations
11. 7 Marks
    aIf network topology never changes, which of the routing protocols, shortest path routing and Distance vector routing is preferred and why?
    How to answer

    • Define shortest path vs distance vector routing
    • Compare need for dynamic updates when topology is static
    • Argue overhead, convergence and simplicity trade-off
    • Conclude preferred protocol with justification
12. 7 Marks
    bExplain the Leaky bucket and token bucket algorithm with Flow charts.
    How to answer

    • Define traffic shaping and congestion control need
    • Explain leaky bucket operation with flow chart
    • Explain token bucket operation with flow chart
    • Compare burst handling and idle behavior
13. 7 Marks
    aExplain layering of protocols. Differentiate between TCP/IP and OSI model.
    How to answer

    • Define protocol layering concept and benefits
    • Outline OSI 7 layers vs TCP/IP 4 layers
    • Differentiate on services, hierarchy and usage
    • Tabulate differences
14. 7 Marks
    bHow does a DNS Resolver bootstrap the domain name lookup process?
    How to answer

    • Define DNS resolver and need for bootstrapping
    • Explain root hints and starting at root servers
    • Describe iterative/recursive lookup steps
    • Explain caching of root and TLD addresses
15. 14 Marks
    Write Short Note on (Any Three):

    1. a)SNMP
    2. b)IMAP
    3. c)TFTP
    4. d)FDDI
    How to answer

    • Select any three from SNMP, IMAP, TFTP, FDDI
    • For each: give full form, purpose and key features
    • Briefly explain operation/message or frame aspects
    • Conclude with use cases