NATIONAL OPEN UNIVERSITY OF NIGERIA
14/16 AHMADU BELLO WAY, VICTORIA ISLAND, LAGOS
SCHOOL OF SCIENCE AND TECHNOLOGY
MARCH/APRIL 2014 EXAMINATION
COURSE CODE: CIT852
COURSE TITLE: DATA COMMUNICATION AND NETWORKS
TIME ALLOWED: 3HOURS
INSTRUCTION: ATTEMPT ANY FIVE (5) QUESTIONS
Question 1
a. Briefly explain the key features of the following:
i. Circuit-switched networks (2.5 marks)
ii. Packaged-switched networks (2.5 marks)
b. State 3 advantages and 2 disadvantages of each of the following network topologies:
i. Bus (2.5 marks)
ii. Star (2.5 marks)
iii. Ring (2.5 marks)
c. List 3 types of broadcast networks (1.5 marks)
Question 2
a. Complete the following table(3.5 marks):
| Layer | Data Package Name |
| Application | |
| Presentation | |
| Session | |
| Transport | |
| Network | |
| Data-link | |
| Physical |
b. With the aid of a table ONLY, outline 5 differences between the OSI reference model and the TCP/IP model. (5 marks)
c. Define the following terms:
i. Baud (1 mark)
ii. Noise (1 mark)
iii. Propagation delay (1 mark)
iv. Attenuation (1 mark)
d. For a constant rate transmission, if it takes 100 seconds to complete 1 transmission cycle, what is the frequency of the transmission? (1.5 marks)
Question 3
a. State 3 drawbacks each of the TCP/IP reference model and the OSI reference model. (6 marks)
b. State 2 approaches to broadcast infrared networking.(2 marks)
c. State 3 characteristics of a connection-oriented service (3 marks)
d. List and explain briefly 3 strategies to manage congestion in a network (3 marks)
Question 4
a. State the 3 steps required for connection establishment in connection oriented services (3 marks).
b. Briefly explain the following concepts:
i. Flooding (3.5 marks)
ii. Link state routing (4.5 marks)
c. State 3 reasons for congestion on a network (3 marks)
Question 5
a. List the steps of the Djikstra routing algorithm (5 marks)
b. Using a table only, highlight 2 differences between congestion control and flow control. (4 marks)
c. For each class of IP4 address, specify the following with the aid of a table containing the following columns: (5 marks)
i. IP address class
ii. Higher order bit
iii. Format
Question 6
a. List the 4 types of routers identified by OSPF and state the function of each router (8 marks).
b. When an application invokes TCP, state and explain briefly what services it receives from TCP (6 marks).
Question 7
d. Explain the following terms:
i. Hierarchical address(2 mark)
ii. Flat address (2 mark)
iii. Static Address assignment (1.5 marks)
iv. Dynamic address assignment (1.5 marks)
v. Adaptive routing (1.5 marks)
vi. Non-adaptive routing (1.5 marks)
e. State 4 features of a token bucket traffic shaper. (4 marks)
For the 2015 – till date past questions for this course CLICK HERE
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