How do you find valid hosts in a subnet?

To find a valid host you need look at what network you're using and what subet maks it is related to.

The valid host will always be in between the Network Address and the Broadcast Address.

Fo example, if you have a network of 192.168.1.0 having the mask of 255.255.255.0 then you'll have only 254 valid hosts. Also, this network relates to Class-C address.