IPv4 Fundamentals

Learn IPv4 addresses, binary boundaries, CIDR, masks, host ranges, and special-purpose ranges.

Concept

IPv4 addresses contain 32 bits. CIDR identifies the network portion with a prefix length, while the remaining bits represent addresses inside that network. The calculator can show the exact binary boundary for an entered address.

Worked example

192.168.1.77/26

256 - 192 = 64
Boundaries: 0, 64, 128, 192

77 is between 64 and 127
Network: 192.168.1.64/26

Try it yourself

Use the subnet calculator and open Show Me the Math to see the calculation for your own address.