AirPort: Reason for 169.254.x.x IP Address
If you have been unsuccessful in trying to connect your AirPort equipped-computer to an AirPort Base Station, then you probably have seen this 169.254.x.x address. The most common reason for getting it is not associating with a base station before trying to use an application that uses TCP/IP such as a Web browser.
It may also indicate that the IP address of the base station is on a different subnet than the connecting computer. In this situation, you will need to manually assign the client computer an address that is on the same subnet before attempting to access the base station.
Remember that if you have the base station set to bridge to an existing local area network (LAN) providing IP addresses from a DHCP server, a wireless client can still obtain a 169.254.x.x address if a server is not found.
Why the 169.254.x.x address?
This 169.254.x.x address, although not an officially private address (as 10.0.0.0 would be), poses little if any chance for conflict with other addresses on the Internet. Open Transport will choose a number randomly in a range of 169.254.0.0 to 169.254.254.255 - a range of over 64,000 possible addresses.
The result of this auto configuration of addresses allows communication automatically with other 169.254.0.0 network addresses on the same LAN without a DHCP server. In other words, Macintosh and Windows-based computers with their default networking configurations installed can communicate with each other on the same LAN automatically.
The auto-configuration of IP addresses is beneficial for workgroups without a professional network administrator, as well as any LAN when its DHCP server is not available or when it has simply stopped working.
It is also very useful when using AirPort equipped-computers on an ad-hoc or computer-to-computer network.
Additional information is available in article 58619: "AirPort Base Station: Reason for 18.104.22.168 IP Address".
Note: Wireless Internet access requires an AirPort Card, AirPort Base Station, and an Internet service provider, for which fees may apply. Some ISPs are not compatible with AirPort. America Online (AOL) works with AirPort software version 2.0 or later. For more information on AOL compatibility, see technical document 106591: "AirPort: How to Use with AOL." Range may vary with site conditions.