Dynamic Host Control Protocol (DHCP) is a client-server protocol created to allow the dynamic assignment of configuration parameters and IP addresses to computers. DHCP is an enhanced version of BOOTP (Bootstrap Protocol). One of the reasons for BOOTP and DHCP is to reduce the ammount of work required by the network administrator. Another reason is to prevent IP address conflicts caused by two computers trying to use the same IP address. If you have read our tutorial on IP addresses, you know that to be useful, IP addresses must be unique on the network in which they exist.
The DHCP server has a pool of addresses from which it draws addresses and then leases them to each client computer as it boots up and connects to the network. The server leases the IP addresses for a period of time set by the DHCP administrator. During the period of the lease, the server will not assign that address to any other computer. When the lease expires, the client must either renew the lease or release the IP address. If the lease expires and the server can no longer communicate with the client or the client releases the address, it will return the IP address to its pool of available addresses.
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