# Create a DHCP Reservation (static IP): enter your HDA MAC address and IP address
Note that if :'''NOTE:''' If the Airport Administration tool forces you to have at least two IP in the DHCP address pool (i.e. if, when entering the same IP address in Ending Address, it adds one to it), it should work fine two. You'll just need to create a second DHCP reservation, and enter any fake MAC address (aa.bb.cc.dd.ee.ff for example).
This will basically allow the DHCP server to only give out one IP address, and it will only give it to your HDA (if your HDA is ever configured to use DHCP, which it shouldn't). All other DHCP requests will be ignored, allowing your HDA DHCP server to be used for all computers on your local network.
Look at a more Refer to [http://discussions.apple.com/thread.jspa?threadID=121990 this site] for a detailed explanation].
BTW, it's much easier if you don't want NAT (i.e. if you have another router that does that), then you can disable both NAT and DHCP by choosing bridge mode.
You just can't disable DHCP alone.