How to master IP Subnetting - Part One - Connected Dots Online
Subnetwork - Wikipedia
In simplest way possible, describe the 'impact' of shifting an IP subnet mask bit one position to the left (assume the starting mask is 255.255.255.0) what does that change accomplish? - Quora
Network Masking - TelecomWorld 101
Why do we need subnet mask? - Quora
What is a Subnet mask?
Subnet Masks & Their Effect
Introduction of Variable Length Subnet Mask (VLSM) - GeeksforGeeks