What wildcard mask is appropriate for advertising the network 128.107.0.0 255.255.255.192 in OSPF?

To derive the appropriate wildcard mask for the network 128.107.0.0 with a subnet mask of 255.255.255.192, we begin by understanding how wildcard masks work in OSPF configuration. A wildcard mask is determined by performing a bitwise NOT operation on the subnet mask.

The subnet mask 255.255.255.192 in binary is represented as:

• 255 = 11111111

• 255 = 11111111

• 255 = 11111111

• 192 = 11000000

This corresponds to:

• /26 (which indicates that the first 26 bits are used for network identification, and the remaining 6 bits can be used for host addresses).

To obtain the wildcard mask, we invert the bits of the subnet mask:

• The inverted bits become:

• 0 = 00000000

• 0 = 00000000

• 0 = 00000000

• 63 = 00111111 (since 256 - 192 = 64)

This leads to the wildcard mask of 0.0.0.63. Using this wildcard mask in OSPF means that the routing protocol