Submission Instructions Please submit your homework solutions by EMAIL to me at Russ.Clark@gatech.edu. Make sure to include [CS3251] in subject line.

Late Policy: You have a total of 3-days for a late budget which you may use for any assignment in a minimum of one day increments.

1. Question 1: DNS

   Use the nslookup command to answer the following questions. You can find nslookup on most any Solaris or Linux system. If you aren't sure where to look, try /usr/sbin/nslookup on acme.

   1. What is the IP address of the authoritative name server for the domains: gatech.edu, cnn.com, whitehouse.gov
   2. What are the IP addresses returned for the hosts: www.gatech.edu, www.cnn.com, www.whitehouse.gov (Try these requests several times. Note the addresses returned in different queries. Explain what is happening.)
   3. Use the MX record to find the mail server for these three domains: gatech.edu, cnn.com, whitehouse.gov

2. Question 2: HTTP

   Review RFC 2616, the HTTP/1.1 specification. Explain the mechanism used for signaling between the client and server to indicate that a persistent connection is being closed. Can the client, the server, or both signal the close of the connection?

3. Question 3: Mail
   1. Create a sample email message as it might appear from a user at gmail.com to another user at gatech.edu. Give the relevant fields and format of the message.
   2. Give the SMTP message flow diagram for the sender delivering this message to the destination mailbox.
   3. Give the POP3 message flow diagram for the recipient retrieving the message from the mailbox.