Answer the questions posed in these case studies fully. Each response should be comprised of at least a short paragraph (if not longer).

A) You are a networking professional who works in a college computer lab. The computers run only the TCP/IP protocol on an Ethernet network, and all computers use 3Com NICs. Many beginning CIT students use this lab for homework; you help them access the network and troubleshoot problems with their connections on a daily basis. One day, a student begins tampering with his computer; when he restarts the computer, it alerts him that it can't find the network. He calls you over to help. You ensure all the physical connections are sound. Then, you check the workstation's network properties and find that he has changed the frame type that his NIC uses to transmit data from Ethernet to token ring. Explain why this has prevented the workstation from connecting to the network.

B) The same student is curious about how a Web site appears on his computer screen. Draw and explain the process that occurs between a client and a server when requesting a Web page. Describe what happens at each layer of the OSI model during this communication.

C) The student appreciates the time you spent explaining what happens to data as it moves through the OSI model layers, but he wonders why he should ever care about the OSI model or data frames. He says he wants to become a network architect and concern himself with routers, switches, and cabling. The student indicates that he doesn't care about the little details like packets. In response, describe how OSI model layers can affect a network's design and networking in general. For example, if the student wants to concentrate on designing a network that makes use of routers, what layer of the OSI model might he take the greatest interest in? How can the OSI model be a useful reference when troubleshooting network problems? For instance, if one node can send and receive data, yet the data is not encoded properly, at what layer of the OSI model might problems be occurring?