19 May 2008 08:26
Dynamic Host Configuration Protocol (DHCP) is an invaluable service when you have a network larger than a handful of computers. It's also a standard component of enterprise networks and sub-networks. Microsoft Windows Server 2008’s built-in DHCP server allows Windows machines (and any other TCP/IP-based machines and devices) to obtain their IP addresses and network settings automatically, which can vastly simplify network configuration. Here, we look at how to install and configure a DHCP server in Windows Server 2008, and explore some of the advanced features DHCP has to offer.
Server Manager (above) is your one-stop shop for adding roles to Windows Server 2008 such as DNS, DHCP and Active Directory. From the Start menu, select | Control Panel | Administrative Tools | Server Manager. Expand and click Roles.
Photo credit: TechRepublic
Choose Add Roles and follow the wizard by selecting the DHCP role. A new DHCP wizard appears to help you configure a DHCP server.
In the previous release of Windows, a wizard did not appear to walk you through creating a DHCP server. Windows Server 2008 has greatly simplified this process by allowing you to configure a DHCP server in roughly seven steps. Of course, you can still manage your DHCP server from the DHCP Microsoft Management Console (MMC) snap-in or delete and create scopes on the fly.
Your network cards and static IP addresses are automatically detected and you can choose how DHCP will service clients on different subnets.
Here you can specify the applicable DNS server(s) to be used with DHCP when an address is assigned.
When you create a scope, you must select the range of IP addresses and specify the appropriate scope options to include. There are two types of scope options: Global and Scope. Global options are propagated to all the scopes that you create on that DHCP server, while Scope options are only for the individual scope that you are working with.
For example, if you have different scopes for several different subnets and each subnet will have a different default gateway but will share the same DNS servers, you would want to set the DNS servers as a Global option while the default gateways would be set separately in each scope as a Scope option.
On the DHCP scope window, you will create your scope. Depending on the size of your network and the amount of users that will be assigned IP addresses, some thought must be given to the parameters of your scope selections. In the above example, we created a simple scope.
You can add multiple scopes before continuing the wizard.
With Windows Server 2008, if you have a router that supports and is configured to take advantage of IPv6, you can enable this functionality on your network.
In previous versions of Windows, you had to install and configure your DHCP server and then authorise it in the DHCP MMC snap-in. Authorising your DHCP server allows you to prevent hackers from configuring rogue DHCP servers. In Windows Server 2008, you have the ability to either authorise the server in the Wizard or authorise it after the fact in the DHCP MMC-snap-in.
You are now ready to review and confirm your settings before applying them.
DCHP settings being applied.
In addition to specifying exclusions, you can add reservations to your DHCP server. By adding a reservation, you ensure that a machine always receives the same IP address from the DHCP server.
1. Right-click on Reservations and choose new reservation.
2. Enter a friendly name for the reservation and the IP address you want to assign to the computer or device.
3. Enter the MAC address of the computer or device. (For Windows machines, you can find the MAC address by running ipconfig/all from the command prompt of the machine.)
4. Enter a description and then choose the following reservation type: DHCP, BOOTP (going across a router), or both, as shown above. Click Add.
In addition to specifying reservations, you can add exclusions to your DHCP server. By adding exclusions, you ensure that machines never receive a DHCP lease for that range of IP addresses. This is very useful to block IP addresses for your servers and routers.
In order to add Exclusions, right-click on Address Pools and choose New Exclusion Range.
The DHCP Microsoft Managment Console (MMC) snap-in.
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