DHCP Server and Relay Agent Commands 863
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DHCP Server and Relay Agent
Commands
DHCP is based on the Bootstrap Protocol (BOOTP). It also captures the
behavior of BOOTP relay agents and DHCP participants can inter operate
with BOOTP participants.
The host RFC’s standardize the configuration parameters which can be
supplied by the DHCP server to the client. After obtaining parameters via
DHCP, a DHCP client should be able to exchange packets with any other host
in the Internet. DHCP is based on a client-server model.
DHCP consists of the following components:
• A protocol for delivering host-specific configuration parameters from a
DHCP server to a host.
• A mechanism for allocation of network addresses to hosts.
DHCP offers the following features and benefits:
• It supports the definition of "pools" of IP addresses that can be allocated to
clients by the server. Many implementations use the term
scope
instead of
pool
.
• Configuration settings like the subnet mask, default router, DNS server,
that are required to make TCP/ IP work correctly can be passed to the
client using DHCP.
• DHCP is s upported by most T CP/ IP ro uters thi s allows i t to allo cate an IP
address according to the subnet the original request came from. This
means that a single DHCP server can be used in multiple subnets and that
there is no need to reconfigure a client that changed subnets.
• Addresses can be leased out for a specific duration after which they need to
be explicitly renewed. This allows DHCP to reclaim expired addresses and
put back in the unallocated pool.
2CSPC4.XCT-SWUM2XX1.book Page 863 Monday, October 3, 2011 11:05 AM