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IP Identifier

Analyze an IPv4 address to determine class, type, and special properties.

How to use the ip address identifier

  1. Paste any IPv4 address.
  2. The tool tells you the class—A, B, C, D, or E—whether it's public or private, and flags any special-purpose use: loopback, APIPA, CGNAT, multicast.
  3. Useful for confirming whether an address can be exposed on the internet.

Frequently asked questions

What makes 100.64.0.0/10 a special CGNAT range?

RFC 6598 reserves 100.64.0.0/10 for Carrier-Grade NAT use. It's not globally routable, but ISPs deploy it on their inside networks instead of doubling-up on RFC 1918.

Why are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 private?

RFC 1918 reserves three ranges for private internal networks. ISPs and the internet backbone won't route them, so multiple organizations can reuse the same addresses without conflict.

Is 127.0.0.0/8 routable on a LAN?

No. The entire /8 is reserved for loopback. Hosts must drop any packet to or from 127.0.0.0/8 received on a non-loopback interface.

N9.254.0.0/16 (APIPA) kicks in when DHCP dies. Two machines on the same segment both grab addresses from this range and can still communicate — a lifeline for troubleshooting.