Concept Guide
3 The client broadcasts a DHCPREQUEST message in response to the oer, requesting the oered values.
4 After receiving a DHCPREQUEST, the server binds the clients’ unique identier (the hardware address plus IP address) to the
accepted conguration 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 conguration parameters are
unacceptable; for example, if the oered address is already in use. In this case, the client starts the conguration
process over by sending a DHCPDISCOVER.
DHCPINFORM A client uses this message to request conguration 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 fulll a DHCPREQUEST; for example, if the requested
address is already in use. In this case, the client starts the conguration 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
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Dynamic Host Conguration Protocol (DHCP)