Section 9.9. Exercises

9.9. Exercises

1.	Find out about an IP address that is well known to you, such as that of your college or your work server. Set up an experiment in which you look up the domain name for this IP address.
2.	Consider DNS servers. Compare two approaches, obtaining a name from a file in a remote machine and from a DNS server of the local ISP. Describe the relationship between a domain name taken from a DNS server and an IP address subnet. In part (b), do all hosts on the same subnet need to be identified by the same DNS server? Why?
3.	Read all the RFCs associated with TELNET and SSH listed in Appendix B. What are the most significant differences between these two protocols? Compare the two protocols on the functionality given by "rlogin."
4.	Read all the RFCs associated with FTP listed in Appendix B. Does FTP compute any checksum for files it transfers? Why? FTP is based on TCP. Explain the status of file transfer if the TCP connection is shut down, and compare it with the same situation in which its control connection remains active. Find all the commands from RFCs set for clients .
5.	Set up an experiment in which two computers across a defined network exchange the same defined file through FTP. Measure the file transfer delay On both directions when the network is in its best traffic state On both directions when the network is in its worst traffic state On one direction when you try FTP from one of the computers to itself
6.	Do research on which letters , such as A, B, C, ..., or signs, such as #, *, , ..., are not allowed to be sent on a URL to a Web server.
7.	Read all the RFCs associated with HTTP listed in Appendix B. What is the purpose of GET command? What is the purpose of PUT command? Following part (a), explain why a GET command needs to use the name of the contacted server when it is applied.
8.	Figure 9.11 shows the hierarchical ASN.1 object identifier of network management. Explain the role of ASN.1 in the protocol reference model, discussing it on either the five- or seven-layer protocol model. Find the impact of constructing a grand set of unique global ASN.1 names for MIB variables . Do research in the related RFCs listed in Appendix B, and find out where in the ASN.1 hierarchy a U.S. based organization must register its own developed MIB.
9.	Consider the SNMP network management environment. Justify why UDP is preferable as TCP for this environment. MIB variables can be read in a local router the MIB belongs to. What would be the pros and cons if we let all managing centers access MIBs in all routers? Should MIB variables be organized in the local router memory the same way that SNMP expresses? Why?
10.	Computer simulation project . Write a computer program to simulate a TCP connection for a client/server combination. The server receives a small file from the client. Set up another machine as the proxy server, and try to send messages from the proxy server to the main server. Display all possible messages in the server.