Disabling Automatic Private IP Addressing (APIPA) on Windows XP Professional Systems

Automatic Private IP Addressing (APIPA) is a Windows feature that assigns a DHCP-enabled network connection an IP address in the range 169.254.x.y in cases where a DHCP server is not available to allocate a legitimate IP address. Designed as a stopgap measure in case the DHCP server is only temporarily off line, a system with an APIPA address will attempt to contact the DHCP server to obtain a valid address at regular intervals.

While APIPA has its uses, some administrators would rather it not exist at all. The good news is that disabling APIPA for a given network adapter is easy enough via a Registry edit. Just follow these steps for a Windows XP Professional system:

1. Click Start > Run. Type Regedit.exe and press OK.

2. Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\Adapters

3. Double click on the IPAutoconfigurationEnabled entry, and change its Value data to 0.

4. Close Regedit and restart.

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of 2000Trainers.com. He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.