Users Guide

3 The client broadcasts a DHCPREQUEST message in response to the offer, requesting the offered values.
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.
Figure 5. Assigning Network Parameters using DHCP
70
Dynamic Host Configuration Protocol (DHCP)