First Homework Assignment
Posted 25 Jan 2004 by herman

Due in class on Friday the 30th, this homework asks you to decipher two fields in an IP header.

The details of the assignment are in homework1.pdf. If anyone finds some clarification is needed, I'll update the document and post an announcement on the course web site.


Solution Comments, posted 2 Feb 2004 by herman
A full solution to this homework can't be given, because part of the answer is for the student to choose an arbitrary Internet host and show its IP address. As for the three packets given, here are some comments:
  1. The two addresses in the first packet are 128.255.44.209, which has the FQDN hpcc19.cs.uiowa.edu, and 128.255.45.255, which has no FQDN. In fact, it does not represent any host --- it is a broadcast address (something I did not cover much in class).

  2. The two addresses in the second packet are 128.255.45.52, which has the FQDN alacran.cs.uiowa.edu, and 216.239.41.99, which has no FQDN address. If you tried to ping 128.255.45.42, it was possibly turned off and you got no response --- you would need to use a tool like the host (or nslookup) command to obtain the FQDN in that case (don't feel bad if you missed this). Some students may have noticed that 216.239.41.99 responds to ping, but that doesn't mean it has an FQDN. Some students noticed that if you type http://216.239.41.99 into a web browser, the Google page returns, leading to the conclusion that 216.239.41.99 belongs to google.com. That may be true, however the IP number doesn't have an official FQDN (don't feel bad if you missed this subtle point).

  3. The two addresses in the third packet are 204.121.3.13, which has the FQDN w11.lanl.gov, and 128.255.45.52, which is alacran.cs.uiowa.edu.

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