An administrator is configuring single-area OSPF on a router. One of the networks that must be advertised is 10.27.27.0 255.255.255.0. What wildcard mask would the administrator use in the OSPF network statement?

In OSPF (Open Shortest Path First) configuration, a wildcard mask is used in network statements to specify which IP addresses should be included. The wildcard mask is the inverse of a subnet mask.

Given the subnet mask 255.255.255.0, we can determine the corresponding wildcard mask by subtracting each octet from 255.

• For the first octet of the subnet mask (255), subtract it from 255: $255-255=0$
• For the second octet (255), do the same: $255-255=0$
• For the third octet (255), again: $255-255=0$
• For the fourth octet (0), subtract it from 255: $255-0=255$

So, the wildcard mask corresponding to the subnet mask 255.255.255.0 is 0.0.0.255.