Users Guide

4. After receiving a DHCPREQUEST, the server binds the clients’ unique identifier (the hardware address

plus IP address) to the accepted configuration parameters and stores the data in a database called a

binding table. The server then broadcasts a DHCPACK message, which signals to the client that it

may begin using the assigned parameters.

There are additional messages that are used in case the DHCP negotiation deviates from the process

previously described and shown in the illustration below.

DHCPDECLINE A client sends this message to the server in response to a DHCPACK if the

configuration parameters are unacceptable; for example, if the offered address is

already in use. In this case, the client starts the configuration process over by

sending a DHCPDISCOVER.

DHCPINFORM A client uses this message to request configuration parameters when it assigned an

IP address manually rather than with DHCP. The server responds by unicast.

DHCPNAK A server sends this message to the client if it is not able to fulfill a DHCPREQUEST;

for example, if the requested address is already in use. In this case, the client starts

the configuration process over by sending a DHCPDISCOVER.

DHCPRELEASE A DHCP client sends this message when it is stopped forcefully to return its IP

address to the server.

Dynamic Host Configuration Protocol (DHCP)