IP type checker
Find out what kind of address an IP is: public, private, loopback, documentation, multicast or reserved. Each answer shows the IANA registry entry and its RFC.
IPv4 address
192.168.1.20Example: type your own address above.
- Address
- 192.168.1.20
- Historical class
- Class C (small networks)
| Block | Name | Reference | Registry |
|---|---|---|---|
| 192.168.0.0/16 | Private-Use | RFC 1918 | IANA Special-Purpose Address Space |
- Block
- 192.168.0.0/16
- Name
- Private-Use
- Reference
- RFC 1918
- Registry
- IANA Special-Purpose Address Space
Registry flags
| Block | Source | Destination | Forwardable | Globally reachable | Reserved by protocol |
|---|---|---|---|---|---|
| 192.168.0.0/16 | Yes | Yes | Yes | No | No |
- Block
- 192.168.0.0/16
- Source
- Yes
- Destination
- Yes
- Forwardable
- Yes
- Globally reachable
- No
- Reserved by protocol
- No
How it works
Most IP addresses are ordinary public addresses, owned by a network and reachable from anywhere. A few ranges are set aside for special jobs. The IANA (the body that hands out internet numbers) keeps two lists of them: the IPv4 and IPv6 Special-Purpose Address Space registries. This page checks an address against both, plus the multicast blocks and the IPv6 address plan.
Private addresses like 10.0.0.0/8, 192.168.0.0/16 and IPv6's fd00::/8 work only inside one network. Documentation ranges like 192.0.2.0/24 and 2001:db8::/32 are for examples and never appear on real networks. Each entry lists five flags: whether the address can be a source or a destination, whether routers forward it, whether it is reachable from the internet, and whether a protocol reserves it.
For email this matters. A mail server that receives your message sees the IP that connected to it, and only a public address can pass SPF (the DNS record listing the servers allowed to send for your domain) or get a PTR record that other servers trust. To check a sender, use the PTR check or the blocklist check. To see which range an address falls in, use IP in range; for addresses that carry an IPv4 address inside them, use IPv4 to IPv6.