Windows NT TCP/IP Network Administration

Chapter 6. Using Dynamic Host Configuration Protocol

The Microsoft Dynamic Host Configuration Protocol (DHCP) Server is a Windows NT Service that automatically assigns IP addresses to clients running DHCP client software. By using DHCP, you can centralize the management of IP addresses, netmasks, and other IP configuration information, greatly reducing the amount of administration needed to maintain a network running TCP/IP transport.

A DHCP client does not have a permanently assigned, hard-coded IP address. Instead, at boot time, the DHCP client requests an IP address from the DHCP Server. The DHCP Server has a pool of IP addresses that are available for assignment. When a DHCP client requests an IP address, the DHCP Server assigns, or leases, an available IP address from that pool to the client. The assigned IP address is then owned by that client for a specified period, called the lease duration.

When the lease expires, that IP address is returned to the pool and becomes available for reassignment to another client. When a client reboots, it checks to see if its lease is still valid. If so, it continues using the same IP address. If not, it requests a new IP address from the DHCP server. Servers and other computers that should always have the same IP address may be assigned a permanent IP address using a DHCP permanent lease.

Many people believe that DHCP is a proprietary Microsoft protocol. It is not, although Microsoft was instrumental in having DHCP adopted as a formal Internet ...