Lab 1

1. The performance of a client-server system is influenced by two network factors: the bandwidth of the network (how many bits/sec it can transport) and the latency (how many seconds it takes for the first bit to get from the client to the server).
   1. Give an example of a data transportation method that exhibits high bandwidth and high latency.
   2. Give an example of one with low bandwidth and low latency.
   3. In what situations would high bandwidth be desired even with high latency?
   4. In what situations would low latency be desired even with low bandwidth?
   5. In commercials that advertise "5 times faster", are they referring to bandwidth or latency?
2. What is the principle difference between connectionless communication and connection-oriented communication?
3. Which of the OSI layers handles each of the following:
   1. Dividing the transmitted bit stream into frames
   2. Determining the route through the subnet to use
4. List two ways in which the OSI reference model and the TCP/IP reference model are the same. Now list two ways in which they differ.
5. Ethernet and wireless networks have some similarities and differences. One property of Ethernet is that only one frame at a time can be transmitted on an Ethernet. Does 802.11 share this property with Ethernet? Discuss your answer.
6. If a binary signal is sent over a 3-kHz channel whose signal-to-noise ratio is 20dB, what is the maximum achievable data rate?
7. What signal-to-noise ratio is needed to put a T1 carrier (1.54 megabits per second) on a 50-kHZ line?
8. The dig command can be used to obtain information from the DNS records for a given domain name or IP address. What is the output for the following commands and what is the difference between them?
   1. dig www.cs.csub.edu
   2. dig soa www.cs.csub.edu
9. You are getting probes from some host in the 209.9.244.* (Class C) network. Which of the following commands will find the Start of Authority record for that network and why?
   1. dig soa 224.9.209.in-addr.arpa
   2. dig soa 209.9.224
   3. ping 224.9.209.in-addr.arpa
10. You are attempting to connect to ftp.foo.com and get the error message
    --- unknown host ftp.foo.com ---
    What is the likely problem and what commands would you use to investigate the problem?
11. Suppose instead you got the message
    Trying 208.207.151.35 ...
    ... Connection timed out.
    How does this differ from the previous error message? What could be causing the issue? How would you investigate it?