I am pretty confident of how to do the subnetting of any paticular class but what i am doubtful about is the concept, when you chose certain number of bits from the host portion in order to be used as subnet bits. Do we use the formula
[b]2 to the power of "n" - 2 [/b] or do we use the formula [b]2 to the power of "n"[/b] .
As i have read it in a number of places that when we put in the 'ip subnet-zero' command on the router we can use the second formula instead of having a minus 2 in our formula but Cisco itself in the CCENT/CCNA ICND1 book says that we use the first formula in order to calculate the number of subnets..
Now can anyone confirm it whether we use the first formula or do we use the second formula when studying for the CCNA examination. Also if you have any link of the CISCO website that says so, it would be great..