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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 class A/B/C/D/E, whether it is public or private, and 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 is not globally routable but ISPs use 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 these three ranges for private internal networks. ISPs and the internet backbone do not route them, so multiple organisations can use the same addresses internally.

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.

What are APIPA addresses used for?

169.254.0.0/16 (APIPA) is auto-assigned when DHCP fails. Two hosts on the same segment will pick addresses in this range and can still talk to each other — useful for diagnostics.