872 Configuring DHCP Server Settings
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. Each 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 
discover requests typically include options for the IP address (option 50), 
subnet mask (option 1), default gateway (option 3), and DNS server (option 
6). These options are predefined.
For options that are not predefined, you can enter the option code and specify 
the data type along with the data that the switch should include in DHCP 
offers. RFC2132 specifies many of the DHCP options. Additional options are 
described in later RFCs.
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DHCPDISCOVER (broadcast)
DHCPOFFER (unicast)
DHCPREQUEST (broadcast)
DHCPACK (unicast)
DHCP Client DHCP Server
(PowerConnect Switch)