COIT20261 Network Routing and Switching

COIT20261 Network Routing and Switching (Term 2 2020)

Assessment item 1—Written Assessment

The first two questions are about working with an IPv4 classless address block. Assume that a company’s ISP has just allocated to them a block of IP addresses that includes the following address: 230.4.178.50/22

Show your calculations for all sub-questions.

Question 1 – Information about the block (3 marks)

1. a) How many addresses are available in the block allocated to the company, including all

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

Create five contiguous subnets from the given block beginning with the first address of the block. The five subnets:

1. The first subnet with 512 addresses
2. A second subnet with 256 addresses

• A third subnet with 128 addresses

1. Two more subnets with 64 addresses each

For each subnet, show its prefix in CIDR format, its subnet address, and its direct broadcast address. Organize the data in a table with a maximum of three columns.

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 them as suggested in some of the tutorial exercises. Some tools you should explore include Wireshark, Ipconfig, Tracert, Netstat, Ping and Arp. All but Wireshark are included in Windows, Wireshark is free to download and install.

In this exercise you will explore three tools: IPCONFIG, TRACERT and PING. Go ahead and do some reading on these tools using online sources, try out these tools yourself. Answer the following question, using your own words, based on your study.

Question: You’ve just installed a command-line only OS and you want to quickly verify that you have Internet connection. Discuss in your own words what each of these three tools (ipconfig, tracert and ping) are designed to do, how they do it, and based on that and your personal exploration of these tools, evaluate how well each tool could give you the information you want.

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 if you assume the following:

• The segment is from an FTP client to an FTP server
• A port number of 56,000 was assigned to this segment
• There are 4 bytes of options
• The server will be instructed not to send any more than 350 bytes at any one time
• The TCP checksum was calculated to equal decimal zero
• The previous segment to this one was acknowledged by the server with an ack/data segment that had an acknowledgement number of 16,000 and a sequence number of 8,000
• 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 rest.

Instructions: briefly (a few words only) explain your answer for each field.