How to Repair DHCP for Windows

Although infrequent, DHCP can have configuration, compatibility, and APIPA faults. However, like many other things, DHCP has two sides and either can have an issue. So, it may take a bit of troubleshooting to identify and then fix the issue. Below are two step-by-step procedures to help you repair DHCP failures: one for DHCP server issues and one for DHCP client issues.

IT Programmer
DHCP issues are common and easily remedied.
credit: curtis_creative/iStock/Getty Images

DHCP Server Problems

Step

If the DHCP server can communicate with the network clients, verify that the DHCP server's IP address is a valid address within the IP address scope configured on the server. Remember that the DHCP server must be assigned a static address from within the address scope.

Step

If the DHCP server is not configuring clients to which it can communicate, verify that the DHCP server is authorized in the Active Directory and the DHCP server service is running on the DHCP server.

Step

DHCP problems can also occur on non-Windows networks that include multiple DHCP servers, especially if they have overlapping IP address scopes. Even if you believe there is only one DHCP server on a network, a rogue (meaning an unintentional setting on a network device that activated DHCP) server may be issuing conflicting addresses. In this case, the remedy is to track down the rogue server and disable its DHCP server services.

Step

A less common issue is an IP address conflict among the DHCP clients. How is this possible? If a client is added to a network and has a static IP address assigned, the client may not ask DHCP for configuration and its manually assigned IP address may duplicate a dynamic address assigned to another client.

DHCP Client Issues

Step

If a DHCP client is not being configured with a network address by the DHCP server, the issue may be that the two nodes are unable to communicate. To determine if this is the problem, open a Command Prompt window and use the "ping" command on the IP address of the DHCP server. If communications are verified, the issue is elsewhere, but if ping indicates no connection, resolve this issue first.

Step

Perhaps the most common DHCP-related issue is when a client fails to obtain an IP address from the DHCP server. In this case, the client defaults to an Automatic Private IP Addressing (APIPA) address with has the values 169.254 in its first two octets.

Step

To remedy this problem: (1.) Open a Command Prompt window (2.) Enter the command "IPCONFIG /ALL" to display the IP address of the client (3.) Verify that the assigned IP address is set to an APIPA address (4.) Restart the client so that a DHCP request is sent to the server (5.) Verify the client's IP address. If the client still has an APIPA adddress, the issue is likely hardware-related.

Step

If after a restart, the client continues to have an APIPA address, verify that the DHCP server has not exhausted the IP address range in its scope. If so, adjust the IP address scope to provide for additional network growth as appropriate.

Step

If after a restart, the client continues to have an APIPA address and the problem isn't elsewhere, it's likely a problem with the client's network adapter or network interface card (NIC). The network adapter could have an incorrect driver or the adapter itself is faulty. The remedy for this issue is to verify that the correct device driver is installed for the network adapter or switch out the network adapter with known-good units.