Subnetting Tutorials
Free guides for network engineers, IT students, and CCNA exam prep.
VLSM Explained Step by Step
Learn Variable Length Subnet Masking with detailed examples.
What is a Subnet Mask?
Understand how subnet masks work at the binary level.
Ultimate CIDR Chart
Printable CIDR reference with subnet masks and host counts.
Wildcard Mask Explained
Wildcard masks and how they differ from subnet masks.
Private IP Ranges — RFC 1918
Complete reference for private IP address ranges.
Classless vs Classful Subnetting
The evolution from classful to CIDR addressing.
Subnet Mask Table
Interactive subnet mask table with PDF download.