Windows XP is configured by default to use the APIPA (Automatic Private IP Addressing) scheme. This scheme allows any Windows XP system that is configured to obtain an IP address automatically from a DHCP server to use an APIPA address if the DHCP server goes down.
However, if you were in the middle of a harried IP connectivity troubleshooting situation, it could be easy to overlook a system that is actually experiencing a connectivity problem due to the fact that it has an IP address—albeit an APIPA address. It would be easier to instantly recognize a problem system if it had no IP address at all.
Fortunately, you can disable APIPA without any repercussions to your network (after all, APIPA doesn't really serve any purpose in a DHCP-based network). Follow these steps to disable APIPA:
- Launch the Registry Editor (Regedit.exe).
- Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters.
- Right-click inside the Parameters subkey and select New | DWORD Value.
- Name the new value IPAutoconfigurationEnabled and press [Enter] twice.
- Verify that the Value Data text box contains a zero (0) and click OK.
- Close the Registry Editor and restart the system to ensure that the changes take effect.
If you decide you want to re-enable APIPA, either delete the IPAutoconfigurationEnabled value or change the Value Data to 1.
Note: Editing the registry is risky, so be sure you have a verified backup before saving any changes.
Stay on top of the latest XP tips and tricks with our free Windows XP newsletter, delivered each Thursday. Automatically sign up today!
Greg Shultz is a freelance Technical Writer. Previously, he has worked as Documentation Specialist in the software industry, a Technical Support Specialist in educational industry, and a Technical Journalist in the computer publishing industry.