April
1999 QUESTION 1 (Compulsory) Total Marks: 20 Marks |
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| (a) | Describe, using a diagram, the three phases of
activity involved in circuit switching.
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[4] |
| (b) | A router may be used to overcome several
differences between different types of network. At which layer in the OSI or TCP/IP model does a router operate? Describe two differences between networks that a router may be used to overcome.
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[5] |
| (c) | What features of electronic mail make it
particularly suitable for transmission by message switching?
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[3] |
| (d) | TCP and UDP are both transport layer protocols
that are used in the Internet. How are they different?
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[2] |
| (e) | List two types of network topologies that are
very susceptible to the problem of a single point of failure? Explain your answer.
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[2] |
| (f) | A repeater is a device sometimes found in long-distance communications systems. Which layer do repeaters operate at? Explain what this device is and why it is employed in data communications. | [4] |