Networking optimize

How do I... Install and configure a DHCP server in Windows Server 2008?

DHCP is an invaluable service when you have a network larger than a handful of computers. Microsoft Windows Server 2008's built-in DHCP server allows Windows machines to obtain their IP addresses and network settings automatically, which can vastly simplify network configuration. Steven Warren describes how to install and configure a DHCP server in Windows Server 2008, and explores some of the advanced features DHCP has to offer.

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. In this document, we'll discuss how to install and configure a DHCP server in Windows Server 2008, and we'll explore some of the advanced features DHCP has to offer.

This blog post is also available as a TechRepublic gallery and TechRepublic download.

Create a plan

Before you configure your DHCP server, it is a good idea to have all your ducks in a row. Prepare and have all the necessary information up front before sitting down and configuring your server. For example, you may need to know:

  • The scope of IP addresses that your server will manage (e.g., 192.168.1.50 to 192.168.1.200).
  • Which machines require static IP addresses (i.e., those machines such as servers and routers that will not use DHCP to receive their IP addresses but will be set manually).
  • Which network information you want to send out to DHCP clients when they get their IP addresses (e.g., the addresses for your default gateway, DNS servers, and WINS servers).

It is much easier to configure your DHCP server with this information in hand rather than scrambling for it at implementation time.

Installing DHCP

Installing a DHCP server in Windows 2008 is a snap. They created a very simple wizard that walks you through the entire process. Follow me on this journey.

To install a DHCP server from the Control Panel, follow these steps:

  1. From the Start menu, select | Control Panel | Administrative Tools | Server Manager.
  2. Expand and click Roles (Figure A).
  3. Choose Add Roles and follow the wizard by selecting the DHCP role (Figure B).
  4. A new DHCP wizard appears to help you configure a DHCP server.

Figure A

Server Manager

Figure B

Add Roles Wizard

In the previous release of Windows, a wizard did not appear to walk you through creating a DHCP server. Windows Server 2008 has really 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.

Let's continue on through the wizard. Your network cards and static IP addresses are automatically detected and you can choose how DHCP will service clients on different subnets, as shown in Figure C.

Figure C

Choose your static IP addresses to service DHCP clients
On the next window (Figure D), you can specify the applicable DNS server(s) to be used with DHCP when an address is assigned. Figure E displays where you would enter the applicable WINS servers if you require it on your network.

Figure D

Enter your DNS server IP address

Figure E

Enter your WINS server IP address

About scopes

When you create a scope, you must select the range of IP addresses and you must specify the appropriate scope options to include. These options are what we were referring to above when we mentioned that you can assign other network information to your clients at the time they are given an IP address.

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 my example (Figure F), I created a simple scope.

Figure F

Creating your scope
The subnet type dropdown allows you to choose wireless as well (Figure G). It defaults to 24 hours. If you want to activate the scope when the wizard is complete, click the Activate this scope checkbox. If you leave it empty, you must activate the scope in the DHCP Microsoft Management Console (MMC) snap-in.

Figure G

You can add multiple scopes before continuing the wizard
With Windows Server 2008, if you have a router (Figure H) that supports and is configured to take advantage of IPv6, you can enable this functionality on your network.

Figure H

Enable IPv6 stateless mode

Authorizing the DHCP server and activating scopes

In previous versions of Windows Server, you had to install and configure your DHCP server and then authorize it in the DHCP MMC snap-in. Authorizing your DHCP server allows you to prevent hackers from configuring rogue DHCP servers. In Windows Server 2008, you have the ability to either authorize the server in the Wizard or authorize it after the fact in the DHCP MMC-snap-in (Figure I).

Figure I

Authorizing your DHCP server
You are now ready to review (Figure J) and confirm your settings before applying your DHCP settings (Figure K).

Figure J

Reviewing your DHCP configuration before applying

Figure K

DHCP installation in progress
Once you have installed the DCHP server, you can manage it from the DHCP MMC snap-in (Figure O) located in Administrative tools. On this screen you can create additional exclusions and reservations.

Adding reservations

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 in Figure L. Click Add.

Figure L

Adding a reservation

Adding exclusions

In addition to specifying reservations, you can add exclusions to your DHCP server (Figure M). 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.

Figure M

Adding an exclusion
In order to add Exclusions, right-click on Address Pools and choose New Exclusion Range as shown in Figure N and Figure O.

Figure N

IP address Exclusion range

Figure O

DCHP MMC snap-in

Troubleshooting DHCP

After configuring DHCP, the easiest way to troubleshoot it is to use Ipconfig from a command prompt. To view all TCP/IP information on a machine just type ipconfig/all. To release a DHCP lease, type ipconfig/release; to renew a lease, type ipconfig/renew.

10 comments
dtrafford
dtrafford

I have some Linux clients inside my network. DHCP works perfectly for all my Windows clients, but the Default Gateway does not get set for my Linux machines. What could it be?

akeem_j
akeem_j

I love the new features especially the authorization of the DHCP with the installation wizard. Thanks

zed.sysadmin
zed.sysadmin

If there is a problem in replicating between Domain controllers, then will the DHCP creates any problem in replicating between DHCP server and other clients? I faced the problem. Could anyone explain why?

jdevine
jdevine

You can also get the MAC address for setting up a reservation by pinging a PC and then running arp -a from the command prompt. This way you do not have to remote in or physically be at the machine.

ashu.bid
ashu.bid

I found this information very good and effective. Thanks

bhavyangraj
bhavyangraj

how do i configure a multiple domain in single exchange server 2003. with internet using.

BALTHOR
BALTHOR

It seems to me that from Windows you are making adjustments in the BIOS and network card.If all of the designed in stuff in the BIOS and network card were not blocked by virus then networking would be automatic.

amitsharmakp
amitsharmakp

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. In this document, we?ll discuss how to install and configure a DHCP server in Windows Server 2008, and we?ll explore some of the advanced features DHCP has to offer. This blog post is also available as a TechRepublic gallery and TechRepublic download. Create a planBefore you configure your DHCP server, it is a good idea to have all your ducks in a row. Prepare and have all the necessary information up front before sitting down and configuring your server. For example, you may need to know: The scope of IP addresses that your server will manage (e.g., 192.168.1.50 to 192.168.1.200). Which machines require static IP addresses (i.e., those machines such as servers and routers that will not use DHCP to receive their IP addresses but will be set manually). Which network information you want to send out to DHCP clients when they get their IP addresses (e.g., the addresses for your default gateway, DNS servers, and WINS servers). It is much easier to configure your DHCP server with this information in hand rather than scrambling for it at implementation time. Installing DHCPInstalling a DHCP server in Windows 2008 is a snap. They created a very simple wizard that walks you through the entire process. Follow me on this journey. To install a DHCP server from the Control Panel, follow these steps: From the Start menu, select | Control Panel | Administrative Tools | Server Manager. Expand and click Roles (Figure A). Choose Add Roles and follow the wizard by selecting the DHCP role (Figure B). A new DHCP wizard appears to help you configure a DHCP server. Figure A Server Manager Figure B Add Roles Wizard In the previous release of Windows, a wizard did not appear to walk you through creating a DHCP server. Windows Server 2008 has really 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. Let?s continue on through the wizard. Your network cards and static IP addresses are automatically detected and you can choose how DHCP will service clients on different subnets, as shown in Figure C. Figure C Choose your static IP addresses to service DHCP clients On the next window (Figure D), you can specify the applicable DNS server(s) to be used with DHCP when an address is assigned. Figure E displays where you would enter the applicable WINS servers if you require it on your network. Figure D Enter your DNS server IP address Figure E Enter your WINS server IP address About scopesWhen you create a scope, you must select the range of IP addresses and you must specify the appropriate scope options to include. These options are what we were referring to above when we mentioned that you can assign other network information to your clients at the time they are given an IP address. 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 my example (Figure F), I created a simple scope. Figure F Creating your scope The subnet type dropdown allows you to choose wireless as well (Figure G). It defaults to 24 hours. If you want to activate the scope when the wizard is complete, click the Activate this scope checkbox. If you leave it empty, you must activate the scope in the DHCP Microsoft Management Console (MMC) snap-in. Figure G You can add multiple scopes before continuing the wizard With Windows Server 2008, if you have a router (Figure H) that supports and is configured to take advantage of IPv6, you can enable this functionality on your network. Figure H Enable IPv6 stateless mode Authorizing the DHCP server and activating scopesIn previous versions of Windows Server, you had to install and configure your DHCP server and then authorize it in the DHCP MMC snap-in. Authorizing your DHCP server allows you to prevent hackers from configuring rogue DHCP servers. In Windows Server 2008, you have the ability to either authorize the server in the Wizard or authorize it after the fact in the DHCP MMC-snap-in (Figure I). Figure I Authorizing your DHCP server You are now ready to review (Figure J) and confirm your settings before applying your DHCP settings (Figure K). Figure J Reviewing your DHCP configuration before applying Figure K DHCP installation in progress Once you have installed the DCHP server, you can manage it from the DHCP MMC snap-in (Figure O) located in Administrative tools. On this screen you can create additional exclusions and reservations. Adding reservationsIn 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. Right-click on Reservations and choose new reservation. Enter a friendly name for the reservation and the IP address you want to assign to the computer or device. 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.) Enter a description and then choose the following reservation type: DHCP, BOOTP (going across a router), or both, as shown in Figure L. Click Add. Figure L Adding a reservation Adding exclusionsIn addition to specifying reservations, you can add exclusions to your DHCP server (Figure M). 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. Figure M Adding an exclusion In order to add Exclusions, right-click on Address Pools and choose New Exclusion Range as shown in Figure N and Figure O. Figure N IP address Exclusion range Figure O