Question 1:
1. Choose all the necessary and suitable MAC address, IP address for interfaces and port addresses implied by the above description. State clearly in your submission the choices you have made for these addresses.!Do not give the addresses in binary but in the X.X.X.X decimal format for the IP addresses, the hexadecimal format for MAC addresses and decimal numbers for the port numbers.!
2. For the delivery of the message from Computer A to Computer B, for each step along the way show the source and destination!
a. MAC addresses!
b. IP addresses!
c. Port addresses!
Making it clear which is the source and which is the destination, in what packet or frame these addresses appear (IP, TCP, Ethernet) and what the order of encapsulation is.!
3. The same as number 2, but for the reply from computer B to computer A!
4. These messages are sensitive. What security vulnerabilities and threats can you see?
What measures would you put in place to remove or minimize the vulnerabilities?!
Question 2 - Subnetting
Consider the following scenarios -!
A) You are an ISP that has been assigned a class B network with the address 145.34.0.0. You know you will service 200 to 250 small companies.!
B) You are a medium-sized company assigned a class B network 156.26.0.0. You have seven divisions and want to assign each of them their own subnet.!
C) You are a small company, of around 100 employees, assigned a class C network. You need to provide three LANs to each of the administration, marketing, and development departments.!
For each of these cases answer the following questions:!
How would you divide up your network to satisfy the requirements? Up to how many hosts can there be in each subnet? Show the slash notation for the subnets and the subnet mask. Is the subnet mask the same for each subnet? For a few of the subnets, show the network address and the broadcast address for the subnet. Are these resulting subnets class C networks?!
Question 3 - Message forwarding
A computer in the Computing Department has just been turned on. The user starts up their web browser and requests to see the Macquarie University home page. The home page www.mq.edu.au resides on a server on the administration subnet.!
Describe what happens in getting this request message to the server and how the server gets the response message back to the client.!
You should assume (for now, because the MQ network is a bit more complex as will be explained in later lectures) there is one router that connects the Computing network to the Administration network. Each of these networks is a switched LAN.!
You should tell the story of the messages, starting from how the browser formats the request, how it progresses through the stack layers. What happens when we get to the Internet layer (since this machine has not contacted the network before)? What happens in the Data Link layer? What does the switch do? What does the router do? What layers are involved at the switch and the router. How does the server stack deliver the packet to the HTTP server software?!