DHCP (Dynamic Host Configuration Protocol) is a protocol based client/server architecture is used to facilitate the assignment of IP addresses in a network. A local network is not using DHCP must provide IP addresses to all computers manually. If DHCP is installed on the local network, then all computers connected in a network will obtain an IP address automatically from a DHCP server. In addition to IP address, many network parameters can be assigned by DHCP, such as default gatewayand DNS server.
Way Of Working
Because DHCP is a protocol that uses client/server architecture, then inDHCP there are two parties involved, namely the DHCP Server and DHCP Client.
The DHCP server is a machine that is running the services that can "rent" of IP addresses and other TCP/IP information to all clients who request it. Some network operating systems such as Windows NT Server, Windows 2000 Server, Windows Server 2003, or GNU/Linux had a service like this.
The DHCP client is the client machine that is running the DHCP client software that allows them to be able to communicate with a DHCP Server. Most operating systems network client (Windows NT Workstation,Windows 2000 Professional, Windows XP, Windows Vista, or GNU/Linux) have software like this.
DHCP server usually has a set of addresses that are permitted to be distributed to clients, referred to as DHCP Pool. Each client then will leasean IP address from a DHCP Pool for the time specified by DHCP, usually up to a few days. While the IP address lease time expires its period, the client will ask the server to assign IP addresses that are new or extend it.
The DHCP Client will attempt to obtain the IP address of the "rental" of a DHCP server in the following four-step process:
DHCPDISCOVER: DHCP client will disseminate requests are broadcast to locate DHCP Server is active.
DHCP Server DHCPOFFER: after hearing a broadcast of the DHCP Client, the DHCP server then offers an address to a DHCP client.
DHCPREQUEST: DCHP Client request the server to lease IP addresses from one of the available address in the DHCP Pool at the specified DHCP Server.
DHCPACK: DHCP server will respond to the request from the client by sending an acknowledgment packet. Then, the DHCP Server will assignan address (and other TCP/IP configuration) to the client database, and update the database. The next client will start the process bindingswith TCP/IP protocol stack and because it already has an IP address, the client can start a communication network.
The four stages of the above only applies to clients who do not yet have an address. For clients who had previously asked for the address to the DHCP server are the same, just stage 3 and stage 4 done, i.e. phase updates the address (address renewal), who is clearly faster process.
In contrast to a distributed DNS system, DHCP are stand-alone, so that if a network there are some DHCP servers, database of IP addresses within a DHCP Server will not be replicated to the other DHCP server. This can be a problem if the configuration of the DHCP server between the two collide, as the IP protocol does not permit the two hosts have the same address.
In addition to providing a dynamic address to a client, the DHCP Server can also assign a static address to the client, so the client will still address from time to time.
Note: the DHCP server should have a static IP address.
DHCP Scope
The DHCP Scope is the IP addresses that can be leased to DHCP clients. This can also be configured by an administrator by using the DHCP server configuration tools. Typically, a leased IP address within a certain period, referred to as DHCP Lease, generally worth three days. Information about the DHCP Scope and IP addresses that have been leased and then stored in the DHCP database in the DHCP server. The value of IP addresses that can be leased must be drawn from the Pool of available DHCP allocated in the network. Errors that often occur in the configuration of DHCP servers is the DHCP Scope configuration error.
DHCP Lease
DHCP Lease rental deadline is the IP address provided to DHCP clientsby the DHCP Server. Generally, this can be configured in such a way by an administrator by using some of the equipment configuration (in Windows NT Server can use DHCP Manager or with Windows 2000 and above can use the Microsoft Management Console [MMC]). DHCP Lease is also often referred to as the Reservation.
DHCP Options
DHCP Options are additional settings for the IP address assigned by DHCP to DHCP client. When a client asks for an IP address to the server, the server will give you at least an IP address and subnet address for the network.
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