DPIT127 Networks and Communications Supplementary Final Assessment (Autumn Session 2020) Page 1 of 2 DPIT127 Networks and Communications Autumn Session 2020 Supplementary Final Assessment (Weighting:...

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DPIT127 Networks and Communications Supplementary Final Assessment (Autumn Session 2020) Page 1 of 2 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 breach 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. (05 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 carrier sense multiple access with collision detection (CSMA/CD) work. (05 marks) 3. Show the equivalent analog sine-wave pattern of the bit string 00110101 using amplitude shift keying, frequency shift keying, and phase-shift keying. (Note: Please clearly identify the voltage levels for each scheme) (05 marks) 4. Code division multiplexing allows multiple users to share a common set of frequencies by 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 binary code of 11110000, and Mobile user B has been assigned a binary code 10101010. The mobile users A transmits a 1, while Mobile user B transmits a 0. Show the sum of products that results and your calculations. (05 marks) 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 172.41.1.0/24 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, broadcast ID and host IDs for each subnet. (05 marks) DPIT127 Networks and Communications Supplementary Final Assessment (Autumn Session 2020) Page 2 of 2 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. (05marks) 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. (05 marks) 8. Explain the difference between circuit switch, packet switch, virtual circuit packet switch and broadcast networks structures? (05 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 0.00024 seconds 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? (05 marks) 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)? (05 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. (05 marks) 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)