DNS on Windows Server 2003, 3rd Edition

Preface

You may not know much about the Domain Name System—yet—but whenever you use the Internet, you use DNS. Every time you send electronic mail or surf the Web, you rely on the Domain Name System.

You see, while you, as a human being, prefer to remember the names of computers, computers like to address each other by number. On an internet, that number is 32 bits long, or between zero and four billion or so.^[1] That’s easy for a computer to remember because computers have lots of memory ideal for storing numbers, but it isn’t nearly as easy for us humans. Pick 10 phone numbers out of the phone book at random, and then try to recall them. Not easy? Now flip to the front of the book and attach random area codes to the phone numbers. That’s about how difficult it would be to remember 10 arbitrary Internet addresses.

This is part of the reason we need the Domain Name System. DNS handles mapping between hostnames, which we humans find convenient, and Internet addresses, which computers deal with. In fact, DNS is the standard mechanism on the Internet for advertising and accessing all kinds of information about hosts, not just addresses. And DNS is used by virtually all internetworking software, including electronic mail, remote terminal programs such as telnet, file transfer programs such as ftp, and web browsers such as Netscape Navigator and Microsoft Internet Explorer.

Another important feature of DNS is that it makes host information available all over the Internet. Keeping information ...