DBIT401 COMPUTER NETWORKS AND MANAGEMENT.

UNIVERSITY EXAMINATIONS: 2016/2017
EXAMINATION FOR THE DIPLOMA IN BUSINESS INFORMATION
TECHNOLOGY
DBIT401 COMPUTER NETWORKS AND MANAGEMENT
DATE: AUGUST, 2017 TIME: 2 HOURS
INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions.

QUESTION ONE [30 MARKS] – COMPULSORY
Imagine you are a consultant being asked to provide advice on the design of a new network. A
company is moving onto a new industrial estate and will be taking over the use of three buildings (A, B
and C). The buildings are only 50 metres apart and the company is aware that a network of
underground cable ducts exists linking the three buildings. All the buildings only have one floor and
each measure about 50 metres by 20 metres. The company will be operating several web servers which
are intended to be accessible from external locations by customers.
Building A contains the company’s main computer room which holds the web servers and also contains
several database and fileservers used by the company’s staff. The building also contains the offices of
some development staff who have very high-performance desktop computers. Their computers
interactively exchange large amounts of data with some of the servers.
Building B contains the office of the clerical staff. They have relatively low performance desktop
computers and their desks are in fixed locations. The workers only exchange a small amount of data
with the servers.
Building C contains the staff cafe and a lounge area. There are also areas used to welcome customers.
Much of the building is open plan and the furniture is regularly moved around.
a) What type of networking should be installed in building A and what equipment or other
facilities would you need? [6Marks]
b) What type of networking should be installed in building B and what equipment or other
facilities would you need? [6Marks]
c) What type of networking should be installed in building C and what equipment or other
facilities would you need? How will you try to provide internet access for visiting customers
without compromising the safety of the company’s own computers? [12Marks]
d) What type of networking and equipment should be used to link together the three buildings and
how will overall Internet access be provided for the company? [6Marks
QUESTION TWO [20 MARKS]
Answer the following questions with regards to the Protocols.
a) Name two data transport protocols provided by the Transport Layer of the OSI model.
[2Marks]
b) Provide a brief description of two services in this layer and indicate what type of application might
use the service. [6Marks]
c) Define the following general terms as used when discussing protocols.
i. Peer
ii. IDU
iii. SDU
iv. PDU
[12Marks]
QUESTION THREE [20 MARKS]
a) Describe the role of a firewall and draw a diagram that shows where a firewall should be
positioned with relation to protecting a local network. [5 Marks]
b) Discuss the techniques that a firewall uses at different levels to prevent external attacks on the
network. [5Marks]
QUESTION FOUR [20 MARKS]
a) Explain how data is transmitted along a fibre optic cable. [6Marks]
b) Identify three physical characteristics of fibre optic cables that make them more suitable for
high speed digital data transmission than copper cables. [6Marks]
c) Describe what is meant by wave division multiplexing (WDM) and explain how it is used to
deliver high rate data transmission over a fibre optic cable. [6Marks]
d) A fibre optic transmission system uses wave division multiplexing with 16 different
wavelengths of light. Each of these wavelengths is able to operate at 2.5Gbps. What is the
maximum data carrying capacity of this transmission system? If you require 4Mbps to stream
one high definition video, determine how many such videos could be transmitted at the same
time using this fibre optic transmission system. [7Marks]
QUESTION FIVE [20 MARKS]
a) A global organization has offices located in different countries around the world and wishes to
connect these together with a network that can transfer data and telephone calls between each
office. Explain how the Internet could be used to provide this network.
[4Marks]
b) What limitations in terms of the Quality of Service it offers does the Internet have in respect of
providing the network described in part A3a)? [6Marks]
c) How does the Quality of Service offered by Multi-protocol label switching (MPLS) differ from
that offered by the Internet? [6Marks]
d) How could the global organization described in part (a) use Multi-protocol label switching
(MPLS) to create its network and explain how MPLS would be able to provide a different
Quality of Service for the transfer of data and telephone calls.
[4Marks]

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