on't need to retain control over a particular part of a network to maintain your e-mail address or Web services-people can follow you around using your domain name. Figuring Out Which Server Knows What When you try to connect to a Web page, for example, http://www.teic.com/, your Web browser splits the URL into its component parts, and determines which part (in this case, www.tcic.com) is the hostname. (We'll refer to the host you are trying to reach as the target.) If you've visited a page on the target recently, your computer will remember the IP address of the host, and send a request for the page to that IP address. If your computer doesn't have the target's IP address, it will connect to whatever local nameserver (NS) you have configured it to use. (Actually, it will most likely connect to one of several local nameservers you've config- ured.) The local nameserver most likely serves multiple machines in your (network) area. If any of the machines served by this DNS server have asked for the target machine recently, the local nameserver will have that machine's IP address stored, and will immediately return that IP address to your computer. If the server does not have the IP address stored, it will try to figure out what remote nameserver has information on the target computer, and retrieve information from there. The first place your local nameserver will ask for information will be one of the root nameservers-1 of 13 computers that stands at the center of the Domain Name System. Every nameserver on the Internet (with limited exceptions) has the IP addresses of these root servers permanently stored. The root nameservers contain information on which nameservers are responsible for which Internet top-level domains (.com, .org, .gov, .edu, and SO on). If you're looking for www.tcic.com, the root server that your local nameserver contacts will point you to several nameservers that contain authoritative information for the .com top-level domain. Once it has the .com server's IP address, your nameserver will ask i