What is DHCP ?
The Dynamic Host Configuration Protocol (DHCP) is an auto configuration protocol used on IP networks. Computers that are connected to IP networks must be configured before they can communicate with other computers on the network. DHCP allows a computer to be configured automatically, eliminating the need for intervention by a network administrator. It also provides a central database for keeping track of computers that have been connected to the network. This prevents two computers from accidentally being configured with the same IP address.
There are two versions of DHCP, one for IPv4 and one for IPv6. While both versions bear the same name and perform much the same purpose, the details of the protocol for IPv4 and IPv6 are sufficiently different that they can be considered separate protocols.
In the absence of DHCP, hosts on an IP network must either use stateless address autoconfiguration to obtain their IP address, or must be configured manually. Because manual configuration is error-prone and time-consuming, it is not in common use. On IPv6 networks, stateless autoconfiguration and DHCP both have advantages, but on IPv4 networks stateless autoconfiguration is only useful for communication on the local subnet, and thus does not compete with DHCP.
There are two versions of DHCP, one for IPv4 and one for IPv6. While both versions bear the same name and perform much the same purpose, the details of the protocol for IPv4 and IPv6 are sufficiently different that they can be considered separate protocols.
In the absence of DHCP, hosts on an IP network must either use stateless address autoconfiguration to obtain their IP address, or must be configured manually. Because manual configuration is error-prone and time-consuming, it is not in common use. On IPv6 networks, stateless autoconfiguration and DHCP both have advantages, but on IPv4 networks stateless autoconfiguration is only useful for communication on the local subnet, and thus does not compete with DHCP.
Source - wikipedia.org
The above diagram diplays a simple structure consisting of a DHCP server and a number of client computers on a network.
The DHCP Server itself contains an IP Address Database which holds all the IP addresses available for distribution. If the client (a member of the network with a Windows 2000 Professional/XP operating system, for example) has "obtain an IP address automatically" enabled in TCP/IP settings, then it is able to receive an IP address from the DHCP server.
Setting Up DHCP
This will serve as a step-by-step guide on how to setup a DHCP server.
Installing the DHCP server is made quite easy in Windows 2003. By using the "Manage your server" wizard, you are able to enter the details you require and have the wizard set the basics for you. Open to "Manage your server" wizard, select the DHCP server option for the list of server roles and press Next. You will be asked to enter the name and description of your scope.
Scope: A scope is a collection of IP addresses for computers on a subnet that use DHCP.
Scope: A scope is a collection of IP addresses for computers on a subnet that use DHCP.
The next window will ask you to define the range of addresses that the scope will distribute across the network and the subnet mask for the IP address. Enter the appropriate details and click next.
You are shown a window in which you must add any exclusions to the range of IP addresses you specified in the previous window. If for example, the IP address 10.0.0.150 is that of the company router then you won't want the DHCP server to be able to distribute that address as well. In this example I have excluded a range of IP addresses, 10.0.0.100 to 10.0.0.110, and a single address, 10.0.0.150. In this case, eleven IP's will be reserved and not distributed amongst the network clients.
It is now time to set the lease duration for how long a client can use an IP address assigned to it from this scope. It is recommended to add longer leases for a fixed network (in the office for example) and shorter leases for remote connections or laptop computers. In this example I have set a lease duration of twelve hours since the network clients would be a fixed desktop computer in a local office and the usual working time is eight hours.
It is now time to set the lease duration for how long a client can use an IP address assigned to it from this scope. It is recommended to add longer leases for a fixed network (in the office for example) and shorter leases for remote connections or laptop computers. In this example I have set a lease duration of twelve hours since the network clients would be a fixed desktop computer in a local office and the usual working time is eight hours.
You are given a choice of whether or not you wish to configure the DHCP options for the scope now or later. If you choose Yes then the upcoming screen shots will be of use to you. Choosing No will allow you to configure these options at a later stage.
The router, or gateway, IP address may be entered in next. The client computers will then know which router to use.
The last step is to activate the scope - just press next when you see the window below. The DHCP server will not work unless you do this.
The DHCP server has now been installed with the basic settings in place.
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