using automatic private ip addressing (APIPA)

the windows xp professional implementation of TCP/IP supports automatic assignment of IP address for simple LAN -based network configurations. this addressing mechanism is an extension of dynamic IP address assignment for LAN adaptors, enabling configuration of IP address without using static IP address assignment or installing the DCHP service. automatic private IP addressing is enabled by default in windows xp professional so that home users and small business users can create a funtioning, single subnet, TCP/IP based network without having to configure the TCP/IP protocol manually or set up a DHCP server.

the process for the automatic private IP addressing feature

• windows xp professional TCP/IP attempts to find a DHCP server on the attached network to obtain a dynamically assigned IP adrress.
• in the absence of a DHCP server during startup (for example, if the server is down for maintanance or repairs) the client cannot obtain an IP address.
• automatic private IP addressing generates an IP address in the form of 169.254.x.y (where x.y is the client,s unique identifier) and a subnet mask of 255.255.0.0 .