Subnetting notes

From Blackcannon wiki

• Gateway address is always the first number of the subnet
• Broadcast address is always the last number of the subnet

to find number of usable hosts

 2^bb-2

the network number is always 2^bb

to find the number of subnets

 divide 256 by 2^bb

to get Subnet Mask

 subtract 2^bb from 256

to get slash notation

 subtract number of bits borrowed from 32