COIT20261 Network Routing and Switching Term 1 2023

Assessment item 1—Written Assessment

The first two questions will require you to work with an IPv4 classless address block. Assume that an ISP has given you a block of IPv4 addresses that includes the following address:

140.66.36.100/22

Using this information, answer Question 1 and Question 2. Show your calculations for all sub- questions.

Question 1 – Information about the block                                                  (3 marks)

1. How many addresses are available in the block allocated to the company, including all special addresses?                                                                                                                (1 mark)
2. What is the network address of the block?                                             (1 mark)
3. What is the direct broadcast address of the block?                                (1 mark)

Question 2– Allocating subnets from a block                                             (7 marks)

Create five contiguous subnets from the given block beginning with the first address of the block, as follows:

1. The first subnet with 512 addresses
2. A second subnet with 256 addresses
3. A third subnet with 128 addresses
4. Two subnets with 64 addresses each

For each subnet, show its prefix in CIDR format, its subnet network address, and its direct broadcast address. Organize your answers clearly in the table below.

Question 3 – Network Tools (Windows)                                                     (5 marks)

Often the best way to gain an initial familiarity with network tools is to simply use them at a basic level, exploring and looking up information as you go. Some common tools you can explore include Wireshark, Ipconfig, Tracert, Netstat, Ping and Arp. All but Wireshark are included in Windows, Wireshark is free to download and install.

The screenshot above is a data frame captured from Wireshark. Read the screenshot carefully and then answer the questions below.

1. In the Network Access Layer, what are the source and destination MAC addresses? (1 Mark)
2. In the Internet Layer, is this an IPv4 or IPv6 packet? what are the source and destination IP addresses? is this packet fragmented or not?                                                                             (2 Mark)
3. In the Transport Layer, what transport protocol is used in the data frame? what are the source and destination port numbers?                                                                                     (1 Mark)
4. What protocol is used in the Application layer? How many bytes does the application layer have?     (1 Mark)

Question 4 – TCP                                                                              (5 marks)

Study a diagram of a TCP segment header, paying special attention to the header fields, then list each field along with the value in decimal that would be in that field given the facts below.

• The segment was sent from a client computer to a HTTPS web server.
• A port number of 63,396 was assigned on the client computer.
• There were no options.
• The client will instruct the server not to send more than 7000 bytes at any one time.
• The previous segment from the server had an acknowledgement number of 13,500 and a sequence number of 7,300.
• The TCP checksum was calculated to equal binary zero.
• The control flag fields indicate states of not urgent; not first (sync request) or final (termination request) segment; no bypass of buffer queues required; and not a reset.

You must briefly explain your answer for each field as per the TCP segment header below.