what is apipa, automatic private ip addressing, how apipa works, how to disable apipa
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what is apipa, how apipa works, and how to disable apipa?

What is APIPA?

APIPA, automatic private ip addressing, is a feature of Microsoft Windows and exists in all popular versions of Windows except Windows NT. It is a DHCP failover mechanism.

APIPA is a common alternative to the use of the Dynamic Host Configuration Protocol (DHCP) to request and retrieve an Internet Protocol (IP) address for a host. APIPA simplifies the assignment of IP address and subnet-mask configuration information to hosts in small networks. When APIPA is used, the operating system allows the assignment of a unique IP address to each station on a small local area network (LAN). This avoids the administrative overhead of running a DHCP server or manually setting IP configuration information.

How APIPA works?

When a DHCP client boots up, it first looks for a DHCP server in order to obtain an IP address and subnet mask. It also allows household users and small business users to create a functional single subnet TCP/IP network without manually configuring the TCP/IP protocol or setting up a DHCP server. This is a dynamic service that means this service is related with DHCP. When a DHCP server fails, APIPA allocates addresses in the private range to Clients verify their address is unique on the LAN using ARP. When the DHCP server is again able to service requests, clients update their addresses automatically.

In APIPA, all devices use the default network mask and all reside on the same subnet.

APIPA is enabled on all DHCP clients in Windows unless the computer's Registry is modified to disable it. APIPA can be enabled on individual network adapters.

Because APIPA uses IP addresses in the private Class B space, APIPA is a feature generally only useful on home or other small intranet LANs.

How to disable APIPA?

In Windows 2000, Windows XP, and Windows Server 2003, it is possible to disable APIPA for all adapters on the system by editing the registry.

To disable APIPA

1. Back up your registry.

2. From the Windows Start menu, choose Run, and then type regedit. The Registry Editor is displayed.

3. Navigate to the key

4. From the Edit menu, choose New DWORD value.

5. Name the value IPAutoconfigurationEnabled and enter a value of 0.

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