DHCP (Dynamic Host Configuration Protocol) make simpler management of IP address configuration by automating address configuration for network clients. All PCs that take part on TCP/IP networks or Internet want to have IP addresses allocated to them and have other IP information organized. IP addresses permit PCs and other network hosts to converse with other PCs or hosts on network.

Some of extra information wanted by network clients may contain a subnet mask, default gateway and DNS server information. Before manually putting all information on every client, DHCP can do this for you automatically.

For DHCP to work you want to have a device acting as a DCHP server. This tool can be a PC, router or other kind of network device. DHCP server is organized with a variety or varieties of IP addresses that can be utilized to provide to clients that request one. It can also be organized with other network parameters as begun previously.

For a client to get information from a DHCP server it should be DHCP enabled. When it is organized this way then it will look for a DHCP server when it begins. This method will vary based on what implementation of DHCP is in use. E.g. in Microsoft implementation of DHCP works as follows:

• Firstly client sends a DHCPDiscover packet and tries to log onto network.

• Then DHCP server that get DHCPDiscover packet replies with a DHCPOffer packet which has an un-leased IP address and any extra TCP/IP configuration information.

• When a DHCP client get a DHCPOffer packet, it then replies by transmitting a DHCPRequest packet that has offered IP address, and displays receiving of offered IP address.

• The chosen DHCP server allows client DHCPRequest for IP address by transmitting a DHCPAck packet and then client can access network.

• DHCP clients attempt to restore their rent when 50 percent of the rent time has ended by sending a DHCPRequest message to DHCP server. They also send this message when they restart to attempt and obtain similar IP configuration back.

The time a client continues its rent on its IP address varies based on how it is setup. The Microsoft period is eight days.

If client PC is setup to utilize DHCP to get its IP address and cannot get a DHCP server then it will probably utilize an APIPA (Automatic Private IP Addressing) address in its place. When using APIPA, DHCP clients can mechanically self organize an IP address and subnet mask for them when a DHCP server is not accessible. IP address range utilized by APIPA is 169.254.0.1 through 169.254.255.254 with a class B subnet mask of 255.255.0.0. The client will utilize this self organized IP address until a DHCP server becomes accessible. So if you are attempting to organize your new DSL router at home and see your IP address is 169.254.x.x when running ipconfig command then it’s probably as it can’t obtain an IP address from router.