A. DHCP is a key service to enable the dynamic allocation of IP addresses to your network. Without DHCP, each machine has to be manually configured with an IP address, gateway, and DNS information. This might work for a small number of servers, but in any sizable environment, the ability for clients to dynamically get IP addresses is vital.

Windows has long had a DHCP service, and it has improved with each new version. In Server 2008 and later, DHCP is a server role that's added through Server Manager. Once you've added the DHCP Server role, you need to configure a scope—a set of IP addresses the DHCP service can allocate from to give to requesting clients. It's important that the DHCP scope you define consists of IP addresses that aren't used on any machine in the network (such as statically defined on a server) nor part of a scope on another DHCP server. Duplicate IP addresses in an environment will cause major problems, and it's always good practice to have an IP allocation scheme and tracking. Some organizations use IP addresses 10-50 of each subnet for servers and printers, 60-240 for DHCP clients, and so on.

Once the DHCP Server role is installed, you need to authorize the DHCP server by navigating to the DHCP Server role in server manager, selecting the server, and selecting Authorize. You can now create a scope.

  1. Navigate to DHCP Server, <server>, IPv4.
  2. Select New Scope from the actions.
  3. Click Next to the introduction wizard screen.
  4. You'll be prompted for a name for the scope and a description. Make it meaningful, such as the IP addresses in the scope, and click Next.
  5. Enter the starting IP address, the ending IP address, and the subnet mask detail and click Next.
  6. DHCP in Windows Server 2008

  7. You can now add specific IP address ranges that should be excluded from the scope. Maybe you have some servers that have IP addresses within the range you're allocating to DHCP, which therefore shouldn't be given to clients. You can also set a delay time, which is the amount of time the DHCP server will wait before responding to DHCP requests. Click Next.
  8. Set the length of time for the IP address lease. The longer the lease time, the less frequent machines have to renew the address—but that means clients keep the address longer. If you have a lot of through traffic of machines on the network, you don't want those machines keeping the lease for long, because your scope will run out of addresses. Set a small lease, maybe a day. Click Next.
  9. You can configure DHCP options, such as default gateway, DNS servers, WINS servers, etc. Or select No and set them later, or at a server level (for things like DNS server etc). Default gateway will likely be different for each scope. Click Next.
  10. Click to activate the scope, and you're done.
  11. If you wanted to select items like DNS and WINS at the server level, the settings apply to all scopes on the server. Select Server Options and you can set global options, as shown here.

DHCP in Windows Server 2008

Once you have DHCP configured, you can run

ipconfig /renew

on your clients and they should get an IP address from your DHCP server. You can see the address with the command ipconfig.