Automatic Private IP Addressing (APIPA)
APIPA allows the dynamic host configuration protocol (DHCP) clients to individually configure an IP address and a subnet mask automatically in situations where the DHCP server is absent. The Automatic Private IP addressing is usually incorporates a number less than twenty-five and is appropriate for non-routed growing businesses.
The addressing can occur on a network if the server is down temporarily or where the network does not have a server. It is useful in providing support and easier configuring of the Local Area Network (LAN).
Areas where APIPA can be applied
Absent DHCP server and expired lease
The lease of the IP address can be re-established by the Windows-based computer and it makes attempts to ensure the process is successful. In situations where it cannot find the DHCP server, it generates an error message before assigning itself with an IP address. The discover message will then be broadcasted by the computer after every few minutes until the server, (DHCP) becomes online. It is followed by a created message which states the re-establishment of communication with the DHCP server.
Initial IP address with an absent DHCP server
An attempt is initiated to notify the default gateway in situations where the computer fails to find the DHCP server after a scan. The originally leased internet protocol address is then is retained by the computer device if the default gateway provides a feedback. In case response is not triggered by the default gateway, then automatic assignment of the IP address is executed by the automatic private IP addressing. The discover information will also be sent after every few minutes after an error message is delivered to the destination.
Absent DCHP server and no initial IP Address
Your computer device will broadcast close to three or several discover messages during the initialization process. Failure of the DHCP server to respond to the broadcasted messages leads to self-assignment by the automatic private IP addressing (APIPA). In situations where it has never had an IP address assigned to it before from a DHCP server, an error message is displayed on the screen. The same process is initiated of retransmitting the discover message until communications are established by the server.
Restrictions of the automatic private IP addressing
- APIPA is limited for use by only the local networks the fact that it is not categorized in any of the ranges of IP addresses described by the Internet Protocol Standard.
- Ping tests cannot be executed directly to the APIPA devices. This means than no other connection requests will be successful on the devices whether in the internet or over the external networks.
- The devices which are configured by the IP addressing are restricted to transmitting messages among the peer devices situated in their local network.
- APIPA does not provide a network gateway address or name server to the client despite offering them an active IP address.
Conflicts are likely to arise within the range of APIPA during an attempt of manual signing of addresses by the local networks. It is important to restrict your network on using the standard IP address ranges to maintain the benefit of IP addressing in determining the failures of DHCP.