Dynamic Host Configuration Protocol

How DHCP Works

DHCP is based on a client/server model, as illustrated in Figure 4.1.

Figure 4.1 The Basic DHCP Model

The network administrator establishes one or more DHCP servers that maintain TCP/IP configuration information and provide address configuration to DHCP-enabled clients in the form of a lease offer. The DHCP server stores the configuration information in a database, which includes:

Valid TCP/IP configuration parameters for all clients on the network.
Valid IP addresses, maintained in a pool for assignment to clients, as well as reserved addresses for manual assignment.
Duration of the lease offered by the server—the length of time for which the IP address can be used before a lease renewal is required.

A DHCP-enabled client, upon acceptance of a lease offer, receives:

A valid IP address for the network it is joining.
Additional TCP/IP configuration parameters, referred to as DHCP options.