I'm having a hard time understanding the answer to the following question:
You have an IP of 220.127.116.11 with a subnet mask of 7 bits. How many hosts and subnets are possible assuming that subnet 0 is not used?
126 subnets and 510 hosts
128 subnets and 512 hosts
510 subnets and 126 hosts
I know the correct answer is 126 subnets and 510 hosts. I believe I understand the 510 hosts. I don't fully understand the 126 subnets. Why do we subtract 2 when we're not enabling subnet zero instead of just 1? I feel like everything I've learned previously indicates we calculate subnets as 2^^n where n indicates the number of bits borrowed for the subnet. I get what the answer is, just don't understand the why.
Thanks in advance!