DHCP

DHCP

• The Dynamic Host Configuration Protocol (DHCP) is a network protocol used to assign IP addresses and provide configuration information to devices such as servers, desktops, or mobile devices. 
• They can communicate on a network using the Internet Protocol (IP). 
• ISC DHCP is a collection of software that implements all aspects of the DHCP (Dynamic Host Configuration Protocol) suite. It includes:

• A DHCP server, which receives clients’ requests and replies to them.
• A DHCP client, which can be bundled with the operating system of a client computer or other IP capable device and which sends configuration requests to the server. 
• A DHCP relay agent, which passes DHCP requests from one LAN to another so that there need not be a DHCP server on every LAN.

Why DHCP?

• Without DHCP, IP addresses for new computers or computers that are moved from one subnet to another must be configured manually.
• IP addresses for computers that are removed from the network must be manually reclaimed.

The DHCP server stores the configuration information in a database that includes:

• Valid TCP/IP configuration parameters for all clients on the network.
• Valid IP addresses, maintained in a pool for assignment to clients, as well as excluded addresses.
• Reserved IP addresses associated with particular DHCP clients. This allows consistent assignment of a single IP address to a single DHCP client.
• The lease duration, or the length of time for which the IP address can be used before a lease renewal is required.

A DHCP-enabled client, upon accepting a lease offer, receives:

• A valid IP address for the subnet to which it is connecting.
• Requested DHCP options, which are additional parameters that a DHCP server is configured to assign to clients.