CS158a Spring 2009Practice Midterm

To study for the midterm I would suggest you: (1) Know how to do (by heart) all the practice problems. (2) Go over your notes at least three times. Second and third time try to see how much you can remember from the first time. (3) Go over what you did on the HW sets. (4) Try to create your own problems similar to the ones I have given and solve them. (5) Skim the relevant sections from the book. (6) If you want to study in groups, at this point you are ready to quiz each other. The practice midterm is below. Here are some facts about the actual midterm: (a) It is closed book, closed notes. Nothing will be permitted on your desk except your pen (pencil) and test. (b) You should bring photo ID. (c) There will be more than one version of the test. Each version will be of comparable difficulty. (d) One problem (less typos) on the actual test will be from the practice test.

1. Define and give an example of the following terms: (a) circuit switched network, (b) packet switched network, (c) internetwork.
2. List each of the layers in the OSI model and say briefly what each does.
3. Give the Java syntax for creating a socket that listen to port 1234 for incoming requests. Show how to accept requests and set up a stream to send strings to the requester.
4. Suppose one is downloading a 1GB file from a satellite orbiting close to the sun with an RTT of 1000s. The bandwidth is 1Mbps. What is the total download time? What is the total number of bits that might be in flight at any given moment?
5. What is tcpdump? Briefly explain how to use it.
6. Briefly explain how frequency hopping spread spectrum and direct sequence spread spectrum work.
7. What is NRZI? What is character stuffing? What is bit stuffing? Give examples.
8. What is the type field of an Ethernet frame for? How can one broadcast a message on an Ethernet? If two host have collided the previous two times they tried to transmit, what is the likelihood they will collide on their next attempt?
9. Briefly describe how a connection is set up when a switched virtual circuit is used.
10. Explain how the bridge learning algorithm we went over in class works.