IP Subnetting Math: Binary, CIDR, Hosts & VLSM
Learn subnetting by calculating it: binary octets with DEC2BIN and BIN2DEC, IP addresses as 32-bit integers, CIDR masks and wildcards, network and broadcast addresses, usable hosts, equal subnets of a /24, VLSM plans and IPv6 /64 counts, every cell checked live.
The first lesson is free — no account needed.
About this course
An IP subnetting course that teaches subnetting by calculating it, on one fictional freight company's networks, for CCNA and Network+ candidates, IT support staff and students. You split octets into bits with DEC2BIN and BIN2DEC and count the 1-bits, turn dotted IPv4 addresses into 32-bit integers and back with INT and MOD, convert CIDR prefixes into subnet and wildcard masks, find the network and broadcast address of any host and confirm it with BITAND, calculate usable hosts with 2^(32 − n) − 2 and size six segments, split a /24 into equal subnets with their host ranges, allocate a VLSM plan for six departments of different sizes and count the /64 subnets in an IPv6 /48. Independent practice, not affiliated with Cisco or CompTIA. CCNA is a trademark of Cisco Systems, Inc. The first lab is free.
Lessons
- Binary ↔ Decimal: Reading an OctetFree
- IPv4 Address ↔ 32-bit Integer Pro
- CIDR Prefix → Subnet Mask & Wildcard Mask Pro
- Network & Broadcast Address from Any Host Pro
- Usable Hosts per Prefix: 2^(32−n) − 2 Pro
- Subnetting a /24 into Equal Subnets Pro
- VLSM: Right-Sizing Subnets for Departments Pro
- IPv6 Basics & the Hosts-per-Prefix Chart Pro