The Dynamic Host Configuration Protocol (DHCP) and Automatic IP Addressing

The Dynamic Host Configuration Protocol assigns IP addresses to Ethernet interfaces on an as-needed basis. When an interface is to be configured by DHCP, it sends out a request at boot time to the designated DHCP server. This request, which is really a RARP query (analogous to ARP, but operating in reverse), carries the MAC address of the interface in question to the DHCP server, which responds with an IP address (and other network settings, such as the netmask) that it knows is available. The booting host then assigns this address to the interface, and the DHCP server sets up a "lease" period so that the host can boot with that same IP address on an ongoing basis.

We will be covering DHCP and how to configure FreeBSD for it in Chapter 35, "Dynamic Host Configuration Protocol (DHCP)."