How many usable subnets with subnet mask 255.255.128.0 with a class B IP address?
The rule is I can't use the first and last subnets. So with a class B IP address and a subnet mask of 255.255.128.0, how many usable subnets will it give me?
255.255.128.0 is the same as 11111111.11111111.10000000.00000000.
That is the same as nnnnnnnn.nnnnnnnn.shhhhhhh.hhhhhhhh.
According to me, the third octet uses one bit for the subnet mask. So if I do 2^1-2, I get 0. That means no subnets. Is this right?