IP Address Ending in Zero

Today the light on my Airport Express began flashing amber and when I launched the Airport Utility, it indicated that the device was unable to obtain a valid IP Address. I looked under Internet -> TCP/IP and the Gateway and DNS Servers had valid IPs, but the IP address of the device has been assigned a link-local 169.254 address, which usually means that DHCP failed to respond. So I unplugged the Airport and hooked up my computer directly to the DSL modem. My computer received the same Gateway and DNS addresses along with a valid public IP. The only oddity was that the public IP ended in zero. Next I dragged out my old wired router. It also received the same x.x.x.0 IP address and worked fine. Then I hooked up the Airport and once again got a valid gateway IP but it failed to assign an IP to the device. I manually entered the IP ending in .0 and it worked, then went back to DHCP and it failed once more. Finally, I reset the modem, received a new IP that didn't end in zero, and the Airport was happy. Does the Airport not support IP addresses ending in zero? It used to be uncommon to assign these out, but with IPs in short supply, ISPs are doing everything they can to make the most of what's left.

I was going to contact Apple Support, but the site is claiming that my complimentary support has expired even though I purchased the device within the past 90 days. I don't feel that I should have to pay Apple to inform them that their product is buggy.