1038 Configuring DHCP Server and Relay Settings
How Does DHCP Work?
When a host connects to the network, the host’s DHCP client broadcasts a
message requesting information from any DHCP server that receives the
broadcast. One or more DHCP servers respond to the request. The response
includes the requested information, such as the IP address, subnet mask, and
default gateway IP address. The client accepts an offer from one of the
servers, and the server sends an acknowledgment to the client to confirm the
transaction.
Figure 32-1. Message Exchange Between DHCP Client and Server
The DHCP server maintains one or more set of IP addresses the and other
configuration information available, by request, to DHCP clients. Ea ch set of
information is known as an address pool.
After a client leases an IP address from the DHCP server, the server adds an
entry to its database. The entry is called a binding.
What are DHCP Options?
DHCP options are collections of data with type codes that indicate how the
options should be used. Options can specify information that is required for
the DHCP protocol, IP stack configuration parameters for the client,
information allowing the client to rendezvous with DHCP servers, and so on.
When a client broadcasts a request for information, the request includes the
option codes that correspond to the information the client wants the DHCP
server to supply. The Web pages and CLI commands to configure DHCP
server settings include many predefined options for the information that is
most commonly requested by DHCP clients. For example, DHCP client
`
DHCPDISCOVER (broadcast)
DHCPOFFER (unicast)
DHCPREQUEST (broadcast)
DHCPACK (unicast)
DHCP Client DHCP Server
(Dell Networking Switch)