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Private IP ranges you should recognize

Private IPv4 ranges are reserved for local networks and are not routed on the public internet. Recognizing them helps avoid confusion during diagnostics.

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What you'll learn
  • Which ranges are private.
  • Why they are not internet-routable.
  • How they interact with NAT and home routers.

The three private IPv4 blocks

10.0.0.0/8

172.16.0.0/12

192.168.0.0/16

Why they exist

They allow organizations and homes to reuse local address space without consuming scarce public IPv4 ranges.

How they appear in practice

Home routers often use 192.168.x.x.

Larger corporate networks may use 10.x.x.x or 172.16.x.x patterns.

Troubleshooting reminder

If you are testing from the public internet, these are not the addresses external sites see.

Always compare them against the actual public address shown by WhenIP.

Related Articles
Public vs private IP: what is the difference?Learn the difference between public internet-facing addresses and private addresses used inside your local network.What is an IP address?Understand what an IP address is, why websites see it, and why it sometimes changes.Reserved IP ranges worth knowingA handy reference for special-use IP ranges that show up in troubleshooting.
Mini FAQ
Is 100.64.0.0/10 private?

It is special shared address space used for carrier-grade NAT, not the classic RFC1918 private space.

Can I port-scan a private address from the internet?

Not unless a tunnel or routing path exposes it externally.

Last updated: March 29, 2026