Dynamic Host Configuration Protocol (DHCP) is an IP standard designed to reduce the complexity of administering IP address configurations.”
Microsoft’s definition. A DHCP server would be set up with the appropriate settings for a given network. Such settings would include a set of fundamental parameters such as the gateway, DNS, subnet masks, and a range of IP addresses. Using DHCP on a network means administrators don’t need to configure these settings individually for each client on the network. The DHCP would automatically distribute them to the clients itself.
The DHCP server assigns a client an IP address taken from a predefined scope for a given amount of time. If an IP address is required for longer than the lease has been set for, the client must request an extension before the lease expires. If the client has not requested an extension on the lease time, the IP address will be considered free and can be assigned to another client. If the user wishes to change IP address then they can do so by typing “ipconfig /release”, followed by “ipconfig /renew” in the command prompt. This will remove the current IP address and request a new one. Reservations can be defined on the DHCP server to allow certain clients to have their own IP address. Addresses can be reserved for a MAC address or a host name so these clients will have a fixed IP address that is configured automatically. Most Internet Service Providers use DHCP to assign new IP addresses to client computers when a customer connects to the internet – this simplifies things at user level.
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.
Set Up & installation
How To Install and Set up a DHCP Server in a Workgroup in Windows Server 2003
This step-by-step article describes how to configure a new Windows Server 2003-based Dynamic Host Configuration Protocol (DHCP) server on a stand-alone server to provide centralized management of IP addresses and other TCP/IP configuration settings for the client computers on a network.
- How to Install the DHCP Service
Before you can configure the DHCP service, you must install it on the server. DHCP is not installed by default during a typical installation of Windows Standard Server 2003 or Windows Enterprise Server 2003. You can install DHCP either during the initial installation of Windows Server 2003 or after the initial installation is completed.
- How to Install the DHCP Service on an Existing Server
- Click Start, point to Control Panel, and then click Add or Remove Programs.
- In the Add or Remove Programs dialog box, click Add/Remove Windows Components.
- In the Windows Components Wizard, click Networking Services in the Components list, and then click Details.
- In the Networking Services dialog box, click to select the Dynamic Host Configuration Protocol (DHCP) check box, and then click OK.
- In the Windows Components Wizard, click Next to start Setup. Insert the Windows Server 2003 CD-ROM into the computer’s CD-ROM or DVD-ROM drive if you are prompted to do so. Setup copies the DHCP server and tool files to your computer.
- When Setup is completed, click Finish.
Setting up a DHCP Server
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.
How to Create a New Scope
- Click Start, point to Programs, point to Administrative Tools, and then click DHCP.
- In the console tree, right-click the DHCP server on which you want to create the new DHCP scope, and then click New Scope.
- In the New Scope Wizard, click Next, and then type a name and description for the scope. This can be any name that you want, but it should be descriptive enough so that you can identify the purpose of the scope on your network (for example, you can use a name such as “DHCP server located in London”). Click Next.
- Type the range of addresses that can be leased as part of this scope (for example, use a range of IP addresses from a starting IP address of 10.0.0.100 to an ending address of 10.0.0.200). Because these addresses are given to clients, they must all be valid addresses for your network and not currently in use. If you want to use a different subnet mask, type the new subnet mask. Click Next.
- Type any IP addresses that you want to exclude from the range that you entered. This includes any addresses in the range described in step 4 that may have already been statically assigned to various computers in your organization. Typically, domain controllers, Web servers, DHCP servers, Domain Name System (DNS) servers, and other servers, have statically assigned IP addresses. Click Next.
- Type the number of days, hours, and minutes before an IP address lease from this scope expires. This determines how long a client can hold a leased address without renewing it.
- Type the IP address for the default gateway that should be used by clients that obtain an IP address from this scope. Click Add to add the default gateway address in the list, and then click Next.
- If you are using DNS servers on your network, type your organization’s domain name in the Parent domain box. Type the name of your DNS server, and then click Resolve to make sure that your DHCP server can contact the DNS server and determine its address. Click Add to include that server in the list of DNS servers that are assigned to the DHCP clients. Click Next, and then follow the same steps if you are using a Windows Internet Naming Service (WINS) server, by adding its name and IP address. Click Next.
- Click Yes, I want to configure this scope now to activate the scope and allow clients to obtain leases from it, and then click Next.
- Click Finish.
- In the console tree, click the server name, and then click Authorize on the Action menu.
The following sections explain how to troubleshoot some of the issues that you may experience when you try to install and configure a Windows Server 2003-based DHCP server in a workgroup.
- Clients Cannot Obtain an IP Address
- If a DHCP client does not have a configured IP address, this typically indicates that the client was not able to contact a DHCP server. This can be caused by a network problem, or because the DHCP server is unavailable. If the DHCP server started and other clients can obtain valid addresses, verify that the client has a valid network connection and that all the related client hardware devices (including cables and network adapters) are working properly.
The DHCP Server Is Unavailable
- If a DHCP server does not provide leased addresses to clients, it is frequently because the DHCP service did not start. If this is the case, the server may not be authorized to operate on the network. If you were previously able to start the DHCP service, but it has since stopped, use Event Viewer to check the System log for any entries that may explain why you cannot start the DHCP service.
To restart the DHCP service:
- Click Start, and then click Run.
- Type cmd, and then press ENTER.
- Type net start dhcpserver, and then press ENTER.
- Click Start, point to Control Panel, point to Administrative Tools, and then click Computer Management.
- Expand Services and Applications, and then click Services.
- Locate and then double-click DHCP Server.
- Verify that Startup is set to Automatic and that Service Status is set to Started. If not, click Start.
- Click OK, and then close the Computer Management Windows.
Configuring a DHCP server
Hereunder is a simple explanation of how to configure a DHCP server.
- The address pool displays a list of IP ranges assigned for distribution and IP address exclusions. You are able to add aexclusion by right clicking the address pool text on the left hand side of the mmc window and selecting “new exclusion range”. This will bring up a window (as seen below) which will allow you to enter an address range to be added. Entering only the start IP will add a single IP address.