Test Papers / Previous Question Papers of IGNOU CS68 Computer Networks December 2005

BACHELOR IN COMPUTER APPLICATIONS
Term-End Examination

December, 2005

CS68 : COMPUTER NETWORKS

Time: 3 hours
Maximum Marks: 75

1. (i) List the five key differences between TCP reference model and OSI reference model. (5)

(ii) Write the similarities and differences between packet and cell switching. (4)

(iii) Why is the data link layer in a LAN subdivided into Logical Link Control (LLC) and Medium Access Control (MAC) sub-layers ? (4)

(iv) List the characteristics of broadband coaxial cable. (5)

(v) Differentiate between virtual circuit and datagrams. (5)

(vi) The maximum payload of TCP segment is 65,515 bytes. Why ? (3)

(vii) What are sliding window protocols ? Explain one-bit sliding window protocol with an appropriate diagram. (4)

2. (i) Name all the basic network topologies and describe advantages of each. Draw proper diagram tor each topology. (5)

(ii) Explain the following terms : (5)
(a) Bandwidth
(b) Channel capacity
(c) Multiplexing
(d) Quality of Service (QoS)
(e) Full-Duplex Transmission

(iii) What is the basic purpose of MAC layer protocol ? Explain the function of following MAC layer protocols :
(a) Ethernet
(b) Token bus (5)

3. (i) Describe the characieristics and application or the following network devices : (6)
(a) Routers
(b) Bridges
(c) Switches

(iii) Answer the following : (9)
(a) Explain ISDN BRI Services.
(b) Differentiate between broadband and baseband services.
(c) Describe the following three fields of TCP header :
(l) Sequence number
(ll) Data offset
(lll) Urgent pointer

4. (i) What is congestion control ? How does it occur ? (5)

(ii) How does TCP handle connection establishment and crash recovery ? (5)

(iii) List and explain any five ISDN applications.

5. (i) Describe and compare the following routing algorithms : (8)
(a) Shortest path routing
(b) Flooding

(ii) How does ATM differ from frame relay ? List and briefly define the ATM service classes. (7)