Instructions Sheet
1. Write all answers in the Microsoft Word File.
2. This examination comprises three parts, Parts A, B and C.
3. Answer all questions in all three parts, Parts A, B and C.
4. Write your answer clearly, and use numbered headings or subheadings to show which part of your answer refers to which question. Example: Question 2 (a).
5. The total number of marks available in this examination is 50.

PART A 10 MARKS
COMPULSORY QUESTIONS
Answer ALL questions from this part.
Answer the following short questions, briefly and clearly.
Question 1 4 Marks
The Maximum Transmission Units (MTUs) range from 296 to 65,535 based on specific protocol used by the system.
(a) Write three advantages of having a large MTU? (3 marks)
(b) What would be an advantage of having a small MTU? (1 marks)
Question 2 4 Marks
The first 10 bytes of an IP packet received at the destination in hexadecimal notation is shown below:
45 0 12 60 00 01 00 00 2D 06
(a) How many bytes of data are being carried by this packet? (2 marks)
(b) What is the higher-level protocol? (2 marks)
Question 3 2 Marks
Compare and contrast CSMA/CD with CSMA/CA.
PART B 20 MARKS
COMPULSORY QUESTIONS
Answer ALL questions from this part.
Answer the following numerical computation questions.
Question 1 6 Marks
A company has been granted a block of addresses which starts at 210.120.XY.0/24, where XY is the last 2 digits of your student ID. Create the following 6 subnets for this company:
(a) 2 subnets with 64 addresses
(b) 2 subnets with 32 addresses
(c) 2 subnets with 16 addresses
Question 2 10 Marks
The figure below shows the configuration of a hypothetical section of the Internet.
(a) Construct the classless routing table of router R1 for this configuration.
(5 marks)
(b) Show the forwarding process if a packet arrives at R1 with the destination address 130.50.0.10. (5 marks)
Question 3 4 Marks
An Ethernet MAC sublayer receives 1510 bytes of data from the LLC layer.
(a) Can the data be encapsulated in one frame? If not, how many frames need to be sent? (2 marks)
(b) What is the size of data in each frame? (2 marks)

PART C 20 MARKS
COMPULSORY QUESTIONS
Answer ALL questions from this part.
Answer the following case study questions.
Question 1 10 Marks
As the network administrator for a growing Internet service provider (ISP), you want to make efficient use of your network addresses. One of the network addresses Internet Assigned Numbers Authority (IANA) assigned to you is a Class C network of 193.167.1.0. You have decided to use the addresses in this Class C network to satisfy the IP address requirements of 16 corporate customers who need between 10 and 14 host addresses each. Calculate a subnet mask that meets their needs.
• List the subnet mask and all subnetwork addresses the mask will create. (5 marks)
• Show detailed calculations for each of your outputs. (5 marks)
Question 2 10 Marks
You work at a help desk and have just received a call from an employee who says her network is too slow. You want the employee to view network statistics (amount of data in and out, etc) using netstat for her Ethernet card.
(a) Write an e-mail to the employee, explaining what command-line program to use and how she can use it to find the information you need. (5 marks)
(b) After following your instructions, the employee tells you that her Ethernet card has transmitted 425838305 non-unicast packets and she has been running the computer only 10 minutes in total. What conclusion can you make from this information?
(5 marks)
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