I will teach about the ``Domain Name System'' (DNS) later on. Students will need some information about domain names before then. Domain names are hierarchical. There are three kinds of ``top domains'': 1. ``Infrastructure Domains'': .arpa is the only one. 2. ``Generic Domains'': .aero, .biz, .com, .coop, .edu, .gov, .info, .int, .mil, .museum, .name, .net, .org, and .pro 3. ``Country Code Domains'': .uk, .de, .jp, .us, etc. You can get more information at (of course) www.iana.org . I know of only one easily accessible place that has a current list of country code domains. That is www.norid.no/domenenavnbaser/domreg.html . (I am sure there are more. This is the one I found first). --- If a domain name ends at (for example) .us it almost certainly is a computer in the USA. If it ends on .nl it almost certainly is a computer in The Netherlands. etc. If it ends on .edu it probably is in the USA, but you can not be sure. For example, there is a computer in the department of Computer Science at the Univ of Toronto with the name www.cdf.toronto.edu . (This dates back to the time before there was a top domain .ca ). So be careful! If you want to find the name of a computer in Egypt, you could go to Google and look for Cairo. You will find candidates like www.cairotimes.com (quite probably in the USA) ce.eng.usf.edu (looks like the Univ of Southern Florida to me) etc. But also www.egyptianmuseum.gov.eg (must be in Egypt). Check: Where is the computer www.norid.no located? A bit more on URLs: In www.norid.no/domenenavnbaser/domreg.html , www.norid.no (almost certainly) is the name of the computer, and /domenenavnbaser/domreg.htm describes the path to the directory/file. Once you know the name (domain name) of a computer, you can use nslookup or dig to find its IP address (IP addresses). And I am sure you have figured out by now that one domain name often ``stands for'' or ``contains'' several computers. Anyone who does not have Google (www.google.com) and IANA (www.iana.org) and IETF (www.ietf.org) and my website (web.njit.edu/~ott) in his/her bookmarks (if you use netscape navigator), or in his/her favorites (if you use microsoft explorer): Get them there!