Introduction

TCP/IP is the de facto standard for computer networking and appears to have no challengers in the networking protocol arena. If you are going to work with Windows Server 2003, you should expect to work with TCP/IP. One of the keys to successfully working with TCP/IP is having an understanding of the concept of TCP/IP addresses. The designers of TCP/IP wanted an identification scheme that was independent of any one computer or network equipment design, so they established a scheme of IP addresses.

If you've ever surfed the Web, you have probably seen IP addresses at one time or another (numbers such as 192.168.144.77). As you administer TCP/IP on a network, a considerable part of your time will be devoted to IP address assignment because IP addresses don't just magically get assigned to network hoststhey have to be provided through manual configuration or some other means. When a computer is added to a network, it needs an IP address to communicate on that network. When the computer moves to a new location, it is likely to need a new IP address. If you are just starting out with managing a large TCP/IP network, you might find the notion of managing all those addresses a bit daunting. If you move a DNS server to a new subnet, you may have to reconfigure every client computer. If you move a client computer to a new subnet, you may have to update its IP address. This does not endear you to road warriors who travel among several offices, especially those who are regional managers. If you manually manage IP addresses, almost any change to the network will require a visit to one or more computers to update TCP/IP configurationsnot a happy prospect. Fortunately, the people who brought us DNS to replace the hosts file also came up with a solution to this dilemma.

DHCP was the Internet community's answer to dynamically distributing IP addresses. DHCP is open and standards-based, as defined by the Internet Engineering Task Force (IETF) in their Requests for Comments (RFCs) 2131 and 2132. (The IETF is the main standards organization for the Internet.) This chapter examines the basics of DHCP as it applies to you, the systems administrator, and how you can use it to make your life and your network better.