The Dynamic Host Configuration Protocol (DHCP) automates the assignment of network parameters to network devices. Even in small networks, DHCP is useful because it makes it easy to add new devices to the network.
DHCP is based on the Bootstrap Protocol (BOOTP), which runs in a static environment where each client has a fixed network connection. For each client using BOOTP, a network administrator must configure a BOOTP parameter file that requires manual intervention to modify. DHCP improves on BOOTP by dynamically allocating IP addresses from an address pool and reclaiming them when they are no longer in use. You can also use DHCP to deliver configuration parameters, such as a configuration file used for startup, to clients.
DHCP is defined in RFC 2131 and enables the automatic configuration of DHCP clients. It removes the need to configure clients individually and consists of two components: a protocol for delivering client-specific configuration parameters from a DHCP server to a client, and a mechanism for allocating network addresses to clients.
DHCP supports dynamic and static allocation of IP addresses. You can use the combination of the two mechanisms.
Dynamic allocation: DHCP assigns an IP address to a client for a limited period (or until the client releases the address).
This mechanism allows automatic reuse of an IP address that is no longer needed by the client to which it was assigned. It is useful for assigning an IP address to a client that connects to the network only temporarily or for sharing a limited pool of IP addresses among a group of clients that do not need permanent IP addresses.
Static allocation: A network administrator assigns an IP address to a client and uses DHCP to deliver this address to the client.
This mechanism allows you to eliminate the error-prone process of manually configuring IP addresses for clients.
Reduced client configurations and costs
Because DHCP is easy to configure, it minimizes operational costs associated with device configurations, eases deployment by non-technical users, and reduces device configuration and maintenance costs at remote sites.
Centralized management
Because the DHCP server maintains configurations for several subnets, an administrator only needs to update a single, central server when configuration parameters change.