Type of Assessment/
Tipe Assessering:
Semester Test 1
Qualification/ BSc IT
Kwalifikasie:
Module code/
Modulekode:
ITRW322
Duration/
Tydsduur:
2
2
Module description/
Module beskrywing:
Computer Networks
Max/
Maks:
40
Examiner(s)/
Eksaminator(e):
Mr Motlokwe Thobejane
Date/
Datum:
08/08/2018
Internal/Interne
Moderator(s):
Mr Petri Jooste
Time/
Tyd:
11:00
hour
uur
SECTION A / AFDELING A
1. Discuss three uses of networks [3]
Home Homes contain many networked devices, e.g., computers, TVs, connected to the
Internet by cable, DSL, wireless, etc.
Home users communicate, e.g., social networks, consume content, e.g., video, and
transact, e.g., auctions
business Companies use networks and computers for resource sharing with the clientserver model
Mobile Tablets, laptops, and smart phones are popular devices; WiFi hotspots and 3G
cellular provide wireless connectivity.
Mobile users communicate, e.g., voice and texts, consume content, e.g., video and Web,
and use sensors, e.g., GPS.
2. Give an overview and comparison of PAN, LAN, MAN and WAN. [10]
Write out the acronym (½)
Give a typical use case (1)
What type of guided transmission media will be prominent (½)
What type of unguided transmission media will be prominent (½)
PAN – Personal Area Network. Small size, smaller than LAN, etc. Transmission media:
e.g. Bluetooth; keyboards, printers, etc.
LAN – Local Area Network. Larger than PAN, used within buildings, etc. Transmission
media: e.g. Twisted Pairs, coaxial; office networks, printers, etc.
MAN – Metropolitan Area Network. Larger than LAN, used to cover a city, etc.
Transmission media: e.g. coaxial, optical fibre, wireless; municipal networks, traffic
monitoring systems, etc.
WAN – Wide Area Network. Larger than MAN, covers a large geographical area such as a
country, commercially owned, etc. Transmission media: optical fibre, satellite, wireless;
Internet, national government network, etc.
3. Compare the TCP/IP reference model and the OSI reference model in two columns. [7 ½]
Write down the OSI layer numbers and names in the first column in the correct order.
Use the second column to write down the corresponding layers of the TCP/IP model
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OSI layers
TCP/IP layers
7
Application
Application
6
Presentation
5
Session
4
Transport
3
Network
2
Data link
1
Physical
Transport
Internet
Host to network
4. Discuss the differences between satellite and fiber optics [4]
5. On which OSI layer does each of the following devices perform its main function: [3]
Router, Modem, Bridge/Switch.
Modem – layer 1; brigde – layer 2; router – layer 3
6. Name and discuss three different services provided by Data link to the Network Layer: [6]
Unacknowledged connectionless service.
Acknowledged connectionless service.
Acknowledged connection-oriented service.
7. For each of the following types of multiplexing: write out the acronym (½), explain how it
functions (1)
[4 ½]
a) TDM
b) FDM
c) WDM
a) FDM (Frequency Division Multiplexing) shares the channel by placing users on
different frequencies
b) WDM (Wavelength Division Multiplexing), another name for FDM, is used to
carry many signals on one fiber
8. Refer to the case of a fast sender and slow receiver to name (½) and explain (1½)
the two types of flow control that can be implemented.
Feedback-based flow control.
• Receiver sends information back to the sender giving it permission to send more
data.
Rate-based flow control.
 The protocol generally has a built-in mechanism that limits the rate at which
the sender may transmit data.
 There is no feedback from the receiver.
 The protocol contains well defined rules about when a sender may transmit
the next frame.
TOTAL/TOTAAL: 42
MAX: 40
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