1. Wrap Up: - Recap - Current topics in networking - What courses next
Wrap Up: - Recap - Current topics in networking - What courses next? - Final exams - Informal chat …

2. Allowed to bring in 2 cheat sheets (4 sides) Syllabus
Thursday, Dec 17
7pm in class
3 hour exam
Should not take more than 2 hours
Allowed to bring in 2 cheat sheets (4 sides)
Syllabus
Everything covered in class from day one
More emphasis (~75%) on Network, Link, Wireless, and Security

3. About the exam format Exact test format
Questions will not test whether you remember
You will not have to write long essays
Not be asked to write code
Will probably have
Multiple choice questions
True and false questions
Some problems to solve
Arguments about tradeoffs
Exact test format
Not yet decided

4. Some Examples:
(T/F) A message is hashed in digital signatures to add an extra layer of security.
(T/F) RTS/CTS solves the hidden terminal problem in WiFi
(T/F) Djikstra’s algorithm computes the spanning tree for node X. This spanning tree is optimal for all nodes in the netwrok graph.
Argue in favor or against: In CSMA, there is no need to freeze a node’ count down when the channel is busy.
Given a network graph, apply Djikstra’s on it and compute the resultant spanning tree.
Suppose all smartphones in UIUC become routers as well as end-points. Thus Alice and Bob can communicate messages with each other by utilizing other smartphones around them as a router/relay. Design a routing scheme for Alice to communicate to Bob (assume that the graph is connected).
For a given graph, compute how many iterations will occur before the distance vector route converges.
Why is TCP called fair? Intuitively argue why this fairness can be achieved.
(T/F) A cellular network engineer tells you that two mobile phones are operating on the same time slot, and same frequency, and they are both associated to the same cell tower. The engineer must be making a mistake.

5. Questions?

6. Some Examples:
(T/F) TCP sends a new packet whenever it gets an ACK (not a DupACK) from the receiver.
(T/F) A TCP sender starts a timer once a packet has been transmitted.
(T/F) Bandwidth constraint does not necessarily imply timing constraints
Argue in favor or against: Stop and wait is never better than GBN
Calculate expected latency when a proxy is, and is not, used for caching webpages.
The network, and relevant data will be provided
Write 2 advantages and 2 disadvantages for recursive and non-recursive DNS
Design a finite state machine for Go-Back-N
Calculate RTO for a given network (relevant data will be given)
Fill out an incomplete figure on TCP’s actions in certain conditions
Prove that TCP flows are fair to each other, irrespective of who starts first
Compute how many iterations will happen before the distance vector route converges.