Q1.(a)What are the functions of the physical layer?
(6 marks)
● Transport bits across network media (Include the layer). > Enables the transport of bits
that make up a data link layer frame across the network media.
● Transform frames into electrical, optical or radio wave signals that represent bits in each
frame.
● Receive complete frames from the data link layer and encode them as signals for
transmission and transmit them to the local media.
● (Can also mention it receives signals from media). The physical layer can also retrieve
signals from the media, restore them to bit representations and pass it to Data Link
Layer as complete frame.
(b)There are three basic forms of network media. The physical layer produces the
representation and groupings of bits for each type of media as: (3 marks)
(i)Copper cable: The signals are patterns of electrical pulses
(ii)Fiber-optic cable: The signals are patterns of light pulses
(iii)Wireless: The signals are patterns of electromagnetic signals using radio or microwave
frequencies
Q2.(a)Differentiate between bandwidth, throughput and Goodput. (6 marks)
● Bandwidth: The capacity of a medium to carry data, measured in bits per second (bps),
Mbps, Gbps, etc. It is the maximum rate at which data can be transferred over a
network.
● Throughput: A measure of the actual data transferred over a given period of time. It
may not always match the specified bandwidth due to various constraints. It is affected
by factors such as traffic type, latency and network devices.
● Goodput: Measure of usable data transferred in a given time, calculated as throughput
minus traffic overhead. It represents the actual useful data transferred after considering
protocol overhead and acknowledgements.
(b)Discuss the application of each of the following UTP cable types. (6 marks)
Cable Type Cable Use / Applications
Used to connect different types of devices, such as a computer
Straight-through cable to a switch or router. The pin configurations at one end of the
cable are the same as the pin configurations at the other end.
Used to connect similar devices, such as two computers or two
Crossover cable switches. The pin configurations at one end of the cable are
reversed at the other end.
Rollover cable Primarily used to connect a computer terminal to a router or
(also known as “Cisco” cable) switch console port for configuration and management
purposes.
(c)When is a wired connection preferred to a wireless connection by an end-user device?
(4 marks)
● When security is a top priority and wired connections are considered more secure than
wireless connections due to the difficulty of intercepting wired signals. > Wired
connection is more secure because data transfer is via ethernet cable while wireless
connection transmits signals through the air, it can be intercepted by other users if not
configured correctly.
● In environments where consistent and reliable network performance is crucial, wired
connections typically offer more stable and faster data transfer speeds compared to
wireless connections.
● For tasks that require high bandwidth and low latency, such as online gaming or video
streaming, where wired connections can provide a more consistent and reliable
connection. (Can remove because it explaint the above point)
● In situations where the wireless network is congested or prone to interference, leading to
potential connectivity issues, a wired connection may be preferred for a more stable
connection. (Extended explanation for above answer)
● In situations where the end device does not have Wireless NIC installed.
Extra questions: (may use google classroom/forum, etc to do discussion)
Question 1 (29 SEPTEMBER 2020)
c)Examine Figure 1-2 below and answer the following questions:
Figure 1-2: TIME Package Deal Advertisement
(i)Among the three data transmission measurements (bandwidth, throughput and goodput),
which type of measurement is shown in TIME’s advertisement? (1 mark)
● The type of measurement shown in the TIME advertisement is bandwidth.
(ii)Discuss the reasons why throughput will never match up with the advertised speed.
(2 marks)
● Throughput will never match the advertised speed due to various factors such as
network congestion, protocol overhead, latency, packet loss and other network
conditions that can affect the actual data transfer rate. In addition, shared network
resources, quality of service settings and the efficiency of network devices can also
affect the achievable throughput.
● Can also include explanation for (bandwidth vs throughput). Bandwidth = the
measurement of the capacity of the medium to transfer data. Throughput = the actual
data transferred over a given period of time.
Q2 a)Different types of network media have different features and benefits. – (Sept 2017 –
TARUC)
(i)Is network media necessary to exist in a network? Justify your answer. (4 marks)
● Network media is essential to the existence of a network because it serves as the
physical medium through which data is transmitted between devices.
● Without network media, communication between devices on a network would not be
possible.
(ii)Differentiate theTHREE (3)basic forms of network media. (6 marks)
● Copper cable: Uses electrical impulses to transmit data, commonly used in Ethernet
networks.
● Fibre-optic cable: Uses light pulses to transmit data, offering high bandwidth and
immunity to electromagnetic interference.
● Wireless: Uses radio or microwave frequencies to transmit data, providing mobility and
flexibility in network connectivity.
(iii)Not all network media has the same characteristics and it is appropriate for the same
purpose. Briefly discussTWO (2)criteria with examples of circumstances for choosing network
media. (8 marks)
● Bandwidth requirements
○ Different applications have varying needs for data speed. For tasks like video
streaming requiring high bandwidth, fiber-optic cable is ideal because it supports
rapid data transfer. On the other hand, for basic data needs, copper cable may
be sufficient.
● Environmental factors
○ Some industrial environments have high levels of electromagnetic interference
that can disrupt data transmission. In such cases, fiber-optic cable, which is
immune to such interference, is preferred for its reliability in maintaining data
integrity.
● The budget allocated
○ Each media type has different costs. For example fiber optic cables will be more
expensive than Unshielded Twister Pair (UTP). You would need to consider the
costs of the media selected based on the budget given.
● The distance the media can carry the signal.
○ Different network media have different ranges where it can carry a signal. If the
requirement is for larger range it is more suitable to use fiber optic cable over
wireless transmission or copper cable.
