Computers & ProgrammingComputers & NetworkingWindows

Disabling Automatic IP Addressing (APIPA)

Automatic Private IP Addressing (APIPA), is a feature of Windows (except Windows NT) operating systems. With APIPA, DHCP clients can automatically self-configure their IP configuration with an IP address and subnet mask when a DHCP server isn’t available.

When a DHCP client boots up, it first looks for a DHCP server in order to obtain an IP configuration. If the client is unable to successfully negotiate a DHCP lease, it uses APIPA to automatically configure itself with an IP address from a range that has been reserved especially for Microsoft.

The IP address range is 169.254.0.1 through 169.254.255.254. The client also configures itself with a default class B subnet mask of 255.255.0.0. A client uses the self-configured IP address until a DHCP server becomes available.

The APIPA service also checks every five minutes for the presence of a DHCP server. If it detects a DHCP server on the network, APIPA stops, and the DHCP server replaces the APIPA networking addresses with dynamically assigned addresses.

How to disable APIPA

Windows XP/Vista/7/200x

  1. Open Registry Editor
  2. In Registry Editor, navigate to the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\adaptername
  3. Create the following entry: IPAutoconfigurationEnabled: REG_DWORD
  4. Assign a value of 0 to disable Automatic Private IP Addressing (APIPA) support for the selected network adapter
  5. Close Registry Editor

If the IPAutoconfigurationEnabled entry is not present, a default value of 1 is assumed, which indicates that APIPA is used.

If multiple adapters are installed, you can disable APIPA for all installed adapters by setting the IPAutoconfigurationEnabled entry (create a REG_DWORD if it does not exist) to 0 at the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

Windows 9x/ME

  1. Open Registry Editor
  2. In Registry Editor, navigate to the following registry key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\DHCP
  3. Create the following entry: IPAutoconfigurationEnabled: REG_DWORD
  4. Assign a value of 0 to disable Automatic Private IP Addressing (APIPA) support for the selected network adapter.
  5. Close Registry Editor.

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