IP Range Reference

The address blocks that hotspots, routers, Docker, VMs, VPNs and clouds use by default. Check a subnet before you set up a network, so it won’t collide with whatever someone plugs in later.

Check a subnet

Rules of thumb

  • IPv4 LAN: pick a random 10.x.y.0/24. Skip 10.0–10.10, 10.42–43, 10.64–127, 10.88–89, 10.96–111 and 10.244.
  • Avoid 172.17–172.31 if anything on the network runs Docker, WSL2 or Hyper-V.
  • 192.168.x is crowded. Anything under ~192.168.10 is a router default somewhere, plus 43, 49, 50, 56, 64–71, 86, 88, 100, 122, 137, 178.
  • Don’t use 100.64.0.0/10 for a LAN. ISPs (CGNAT) and Tailscale already live there.
  • IPv6: use fd + 40 random bits for your /48. Never use fc00::/8 or a hand-picked fd00::.

How crowded is each block?

10.N.0.0/16N = 0 → 255
172.Y.X.0/20Y = 16 → 31 (rows) · X = 0 → 240 (cols)
192.168.N.0/24N = 0 → 255
no known defaultminorsomebusyvery busy
Hover a cell to see what uses it. Click to check it.