D-Link DFL-600 - Manual (Page 57)

In the case shown above, the DFL-600’s WAN port was connected to a
10.0.0.0 network
− with a subnet mask of 255.0.0.0. The LAN ports used the
default 192.168.0.0 network addresses, and the DMZ port used the default
192.168.1.0 network addresses
− both with a subnet mask of 255.255.255.0.
The 0.0.0.0 IP address signifies the Broadcast address
− the address within
the DFL-600 where all packets that have an unknown destination address are
forwarded. The DFL-600 then relates the 0.0.0.0 IP address to the WAN’s
gateway address of 10.254.254.251. This route is labeled as the Default
route, and leads to the Internet.