As with Class C and Class B, the numbers are the same; we just start in the second octet.

If your host ID is 10.20.80.30 /20,

what is your subnet, broadcast address, and valid host range?

Mask?

First, determine the block size and then identify the valid subnets. Interesting octet?

Block size?

Valid subnets?

Where does the host address fall within the valid subnets?

What is the broadcast address of this subnet?

What is the valid host range?