My Windows 2000 DHCP client has an IP address not in any scopes, how?

A. Microsoft have tried to make Windows 2000 as easy to setup on asmall network as possible and by default and machines installed are setup to useDHCP. On a very small network you may not have a DHCP server and rather than themachines failing to initialize TCP/IP Microsoft has added code so that themachines will use an address not in use on the local network in the class Baddress range 169.254.x.x. This IP address range is reserved for internal useonly and soshould not clash with any "real" IP addresses on your network. TheMacOS uses the same address range for its DHCP clients when a DHCP server cannotbe contacted as does Windows 98 Second Edition.

This DHCP address allocation uses conflict detection via a NetBIOS namingbroadcast over DHCP so each machine gets an IP address from the 169.254.x.xrange which is not in use. The actual address initially chosed in random.

If any of your machines have a 169.254.x.x address it just means they couldnot contact a DHCP server so check your network connectivity.

This automatic IP addressing is known as Automatic Private IP Addressing (APIPA).