Regex: ipv4 address

How it works

Four octets, each constrained to the real 0–255 range: 25[0-5] covers 250–255, 2[0-4]\d covers 200–249, 1\d\d covers 100–199, [1-9]?\d handles 0–99 without leading zeros.

Honest caveats

Matches format, not meaning — 0.0.0.0 and broadcast addresses pass. For subnet logic (is this IP in 10.0.0.0/8?), use a CIDR calculator, not a regex.

More patterns