DHCP Server

DHCP (Dynamic Host Configuration Protocol) is a system implemented in a network equipment (usually a router but it may be also a wireless access point for example) or a PC (usually a network server) Which automatically assigns a unique IP address to each PC connected to the LAN within a given range. These must necessarily be configured in dynamic IP. This feature simplifies the IP configuration of an internal network.

When a computer connects to the network (usually at startup), it sends a special message to the address 255.255.255.255 (a broadcast) via network port 68 (TCP) on Ethernet. If a DHCP server is connected to the network, it will respond with a particular broadcast containing the IP address and netmask) for this PC. If the connected computer accepts this configuration, it will respond to a server that accepts the IP address and mask.

The server will reserve that address for a period defined in the DHCP service (a few hours to several days). When the lease is finished, computer will reapply a new IP configuration to the server.

Client computers must be configured to automatically receive their IP address and netmask dynamically. If a computer did not detect a DHCP server and no alternative configuration, the APIPA assigned an address in the range 169.254.XX which is private. This address range can not connect over the Internet.

Related Definitions: IPconfig and winipcgf commands - Lan network - firewall - protocols - Model TCP / IP