DHCP (Dynamic Host Configuration Protocol) abridges the management of IP address pattern by automating address pattern for network clients. All computers that contribute on TCP/IP networks or the Internet need to have IP addresses allocated to them and have other IP information configured. IP addresses permit computers and other network hosts to converse with other computers or hosts on the network.

Some of the extra information wanted by network clients may comprise a subnet mask, default gateway and DNS server data. Rather than physically inputting all of this information on every client, DHCP can do this for you mechanically.

In sequence for DHCP to work you require to have a device acting as a DCHP server. This device can be a computer, router or other kind of network device. The DHCP server is arranged with a range or ranges of IP addresses that can be employed to give to clients that request one. It can also be configured with other network parameters as affirmed earlier.

For a client to be able to get data from a DHCP server it must be DHCP allowed. When it is configured this way then it will search for a DHCP server when it starts up. This process will vary conditional on what completion of DHCP is in use. For example in the Microsoft completion of DHCP works as follows:

The client emits a DHCPDiscover packet the first time the client efforts to log onto the network.

Then the DHCP server that obtains the DHCPDiscover packet reacts with a DHCPOffer packet which contains an un-leased IP address and any extra TCP/IP configuration data.

When a DHCP client obtains a DHCPOffer packet, it then reacts by broadcasting a DHCPRequest packet that contains the offered IP address and illustrates acceptance of the offered IP address.

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

DHCP clients attempt to renew their lease when 50 percent of the rent time has expired by sending a DHCPRequest message to the DHCP server. They also send this message when they resume trying and obtaining the same IP configuration back.

The amount of time a client keeps its rent on its IP address varies conditional on how it is setup. The default Microsoft duration is 8 days.

If the client computer is system to use DHCP to get its IP address and cannot discover a DHCP server then it will most possible utilize an APIPA (Automatic Private IP Addressing) address in its place. When using APIPA, DHCP clients can automatically self configure an IP address and subnet mask for them when a DHCP server is not available. The IP address variety 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 use this self configured IP address until a DHCP server becomes obtainable. So if you are trying to arrange your new DSL router at home and notice your IP address is 169.254.x.x when running the ipconfig control then it’s most likely because it can’t obtain an IP address from the router.