CS158a Spring 2023Practice Midterm

Studying for one of my tests does involve some memorization. I believe this is an important skill. Often people waste a lot of time and fail to remember the things they are trying to memorize. Please use a technique that has been shown to work such as the method of loci. Other memorization techniques can be found off the Wiki Page for Moonwalking with Einstein. Given this, to study for the midterm I would suggest you:

• Know how to do (by heart) all the practice problems.
• Go over your notes at least three times. Second and third time try to see how much you can remember from the first time.
• Go over the homework problems.
• Try to create your own problems similar to the ones I have given and solve them.
• Skim the relevant sections from the book.
• 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. Briefly define and contrast the following concepts: (a) Circuit-Switched versus packet-switched networks, (b) STDM versus FDM.
2. Give the 7 seven layers of the OSI model and briefly say the roles of each.
3. Give an example of how to use each of the following network tools: (a) ping, (b) dig, (c) ifconfig, (d) traceroute, (e) tcpdump, (f) nmap
4. Suppose we had a channel with a signal to noise ratio of 500 and a bandwidth of 6000Hz. What would be an upper bounded on the number of bits per second we can communicate over this channel? Briefly explain NRZI and Manchester encoding.
5. Suppose we are computing a CRC-15 of 2KB of data using the generating polynomial `x^15+ x^14+1`. Based on what we learned in class what kinds of errors would we be able to detect?
6. Briefly explain how the sliding window protocol works, where it might be used in what we have covered so far. Then explain what negative acknowledgement areas.
7. Explain the hidden nodes and exposed nodes problems in connection to wireless networks.
8. Give a concrete example of how the distributed spanning tree algorithm from class works and how it is used in the construction of bridge forwarding tables.
9. List the contents of a link state packet. Give an example illustrating how Dijkstra's algorithm works.
10. Explain how auto-configuration of addresses works in IPv6.