IP Addressing

APIPA

Automatic Private IP Addressing (APIPA) is a fallback mechanism built into modern operating systems that automatically assigns an IPv4 address from the range 169.254.0.0/16 when a device configured for DHCP fails to obtain an address from a DHCP server. This feature ensures that the system remains capable of limited local communication rather than being left without an IP address altogether.

APIPA ensures LAN connectivity by having every host that fails to obtain a DHCP lease automatically assign itself an address from the same reserved block. This range is globally standardized as a link-local network, meaning it is reserved specifically for this purpose and is treated consistently across all systems that implement it.