State the main advantages of the OSI 7-layered model, giving
examples of each of the layers. Also, with reference to the OSI
model, outline how TCP/IP fits into the model, and the functions
that it implements. (10)
(b)
Outline, with the aid of diagrams, the three main network
topologies, and how well they cope with network traffic. Also
highlight their main disadvantages, and how they could be overcome.
(15)
2
(a)
Discuss how ATM deals with real-time and non-real-time
traffic. Outline the advantages that ATM has over traditional
networks technologies, such as Ethernet. (12)
(b)
Explain, with the use of an example, how ATM cells are routed.
Explain also how the VCI virtual paths and circuits to route cells.
(13)
3
Explain the methods that a hacker might use to tamper
with a network. Outline the level of difficulty in implementing
the methods, and also how easy it is to detect that they have
occurred. (25)
4
(a)
Discuss the main fields in the TCP header
and outline how two application programs can communicate over
a network using TCP. (15)
Outline the usage of Class A, Class B, Class C and Class
D IP addresses, and estimate the maximum number of hosts that
can connect if an organisation is granted a Class B address.
(10)
5
(a)
Identify the usage of each of the fields of an
IEEE 802.3 data frame. (12)
(b)
Show how a network could be set-up using segment switches
and network hubs. What advantages do switches have over conventional
hubs? Also, explain the advantages of store-and-forward switching.
(13)
6
(a)
Discuss the main techniques that a firewall would
use to filter incoming and outgoing TCP/IP packets. (12)
(b)
Outline how SMTP transmits email messages. Explain how MIME integrates
with this to support file attachments. (13)
