DPIT127 Networks and Communications
Supplementary Final Assessment (Autumn Session 2020)
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DPIT127 Networks and Communications
Autumn Session 2020
Supplementary Final Assessment (Weighting: 30%)
Total Marks: 60
Due Date: 26th June 2020 (Friday 03:00 pm). Submit your file to the Turnitin
submission link on the subject Moodle site.
Please read all the instructions given in each question carefully.
Academic Integrity: Your submission must be completely your own work. If it is
suspected that you have received assistance, eg, from an electronic source or
another person, the matter can be investigated as an alleged
each of the UOW
College Academic Integrity and Student Conduct Policy, in accordance with the
Procedure for Managing Alleged Student Misconduct. Please note, as part of
this investigation, you may be required to undergo an oral examination to verify
your understanding of the assessment content.
PART A: Short Answer Questions (12 x 5 = 60 Marks)
1. What is the different between a Router and a Switch? Justify your answer with
appropriate explanation and diagrams. XXXXXXXXXX05 marks)
2. Medium access control protocols allow devices to ‘take turns’ at transmitting data. Two
major types of medium access control protocols are: contention-based and round robin
protocols. With use of a diagram/flowchart or otherwise explain how the ca
ier sense
multiple access with collision detection (CSMA/CD) work. XXXXXXXXXX05 marks)
3. Show the equivalent analog sine-wave pattern of the bit string XXXXXXXXXXusing
amplitude shift keying, frequency shift keying, and phase-shift keying.
(Note: Please clearly identify the voltage levels for each scheme XXXXXXXXXXmarks)
4. Code division multiplexing allows multiple users to share a common set of frequencies
y assigning a unique digital code to each user. Let us consider an example of 2 mobile
users A and B who use code division multiplexing. Mobile user A has been assigned a
inary code of XXXXXXXXXX, and Mobile user B has been assigned a binary code
XXXXXXXXXXThe mobile users A transmits a 1, while Mobile user B transmits a 0. Show
the sum of products that results and your calculations XXXXXXXXXXmarks)
5. A company has 240 workstations in their head office and the IT manager would like to
assign a subnetwork address for each department. He wants to create 8 subnets using
the XXXXXXXXXX/24 block and assign the first subnetwork to their servers and the rest for
their 200 workstations. How will we compute the subnetwork requirement? Clearly,
identify the network ID,
oadcast ID and host IDs for each subnet XXXXXXXXXXmarks)
DPIT127 Networks and Communications
Supplementary Final Assessment (Autumn Session 2020)
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6. In an internet networking environment, TCP/IP protocol suite is used to define
functions performed by different networking components, based on Open Systems
Interconnections (OSI) model. Using a diagram, identify how the OSI model and the
TCP/IP Protocol suite are mapped with each other XXXXXXXXXX05marks)
7. Using the flooding technique on the network graph shown in the figure below, how
many packets will be created if a packet originates at node A and the network hop limit
is set to 2? The cost of each path in the network is shown in the Figure below.
XXXXXXXXXX05 marks)
8. Explain the difference between circuit switch, packet switch, virtual circuit packet
switch and
oadcast networks structures? XXXXXXXXXX marks)
9. How does the size of a key affect the strengths and weaknesses of an encryption
technique? Consider both a friendly use of the key and an unfriendly use of the key.
Assume a key is 28 bits. If it takes a computer XXXXXXXXXXseconds to try each key, how
long will it take to try all possible keys? What if 1000 computers are working together
to try all keys? What if the key is 64 bits in length? XXXXXXXXXXmarks)
10. What is the reliability of a modem if the MTBF is 3000 hours and a transaction take 15
minutes, or 1/4 of an hour (0.25)? XXXXXXXXXX marks)
11. A company has two offices located approximately 1 mile apart. The company requires
data transfer between these two offices at speeds up to 100 Mbps. List as many solutions
as possible for interconnecting two offices. Justify the answers by understanding
technical, financial, and political feasibilities XXXXXXXXXXmarks)
12. You have a computer at home with a wireless NIC and wireless router. List all the
security measures that should be employed so that your home network is secure.
(05 marks)