To master subnetting, you must look past the decimal numbers you see on your screen and understand how a computer views an IP address. Computers do not understand 192.168.1.1 ; they only understand bits: ones ( ) and zeros ( Understanding the 32-Bit IPv4 Address
Subnetting is the process of partitioning a single physical network into multiple, smaller logical sub-networks (subnets).
He began "borrowing bits" from the host side like a pro.Take a bit from the right.Give it back [3, 4].