TCP/IP: Try It At Home

There are three versions of the worksheet: one for Windows XP, one for Windows Vista, and Mac OS X. If you have some problems running the commands on the worksheet, you can look here to get a sample of what the output looks like. This is what I got when I ran the commands on my home PC around 6 AM EST on March 6, 2007. The results might be a little different on another PC or at another time.

In the DOS command window, type ipconfig /all and hit <enter>. What is your IP address? What are the IP addresses of your DNS servers?
In the DOS command window, type nslookup www.google.com and hit <enter>. This does a DNS lookup of the server www.google.com. What does it say is its IP address?
In the DOS command window, type ping www.google.com and hit <enter>. Does it find it? If so, what is the IP address? Type Google's IP address into the address bar of your browser and hit <enter>. What happens?
In the DOS command window, type tracert www.google.com and hit <enter>. Observe the route that packets take to their destination. Copy down the last 2 lines of output before the "Trace complete" message. Note the last IP address. Where have you seen it before?
In the DOS command window, type telnet www.google.com 80 and hit <enter>. The screen should change to what looks like a blank screen with "telnet www.google.com" in the title bar at the top. You will not be able to see the letters that you type now, so you must carefully type the following:
GET /index.html HTTP/1.0
(make sure you get the upper and lower case correct) and then hit <enter> several times, until you see "Connection to host lost." and you are back at the command prompt. Can you figure out what all that junk is? (Hint: the text you typed in starting with GET is exactly what a browser sends to a web server.) Don't give up too quickly …
Using your browser, go to http://www.networksolutions.com/en_US/whois/index.jhtml and see if you can figure out who the IP address 69.63.187.12 belongs to. Who does the domain name extremities.com belong to?
In the DOS command window, run the command netstat -s -p IP. How many IP packets have been received?
Now wait about 30 seconds, and run the command again (use the up-arrow key, remember?) Now how many packets have been received? You will probably see that the number of packets goes up, even though you haven't done anything.
Now use your browser to connect to a web site or download a file, and run the command once more. Now how many IP packets have been received?
To see all the things you can do with netstat, type netstat -?. What does netstat -r do?
Go to http://www.whatismyipaddress.com. What does it say is your IP address? Is it the same as you got from netstat /a for question 2? Is the map it shows of your location close to correct?