Special-Use & Reserved IP Checker

An IP address is private if it falls inside one of the reserved private ranges defined by RFC 1918: 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16. It is public if it does not fall inside any reserved or special-use range and is therefore globally reachable on the internet. There are also other non-public ranges that are not strictly RFC 1918 private, such as 100.64.0.0/10 for carrier-grade NAT and 169.254.0.0/16 for link-local addresses. The reliable way to check is to test the address against the full IANA Special-Purpose Address Registry rather than the three RFC 1918 ranges alone.

The 100.64.0.0/10 range is Shared Address Space defined by RFC 6598. It is used by internet service providers for carrier-grade NAT, also called CGNAT, where many customers share a pool of addresses behind the provider network. It is not part of the RFC 1918 private ranges and it is not globally reachable on the public internet. If you see an address in 100.64.0.0/10 on your router, it usually means your provider is placing you behind carrier-grade NAT instead of giving you a public IP address.

No. The 169.254.0.0/16 range is the IPv4 Link-Local range defined by RFC 3927, often called APIPA on Windows systems. A device assigns itself an address in this range automatically when it cannot reach a DHCP server. These addresses work only on the local network segment, they are not globally reachable, and routers do not forward them across the internet. A device showing a 169.254 address usually indicates a DHCP or network connectivity problem rather than a working internet connection.

The reserved and special-use IPv4 ranges defined by the IANA Special-Purpose Address Registry include 0.0.0.0/8 for this network, 10.0.0.0/8 for private use, 100.64.0.0/10 for carrier-grade NAT, 127.0.0.0/8 for loopback, 169.254.0.0/16 for link-local, 172.16.0.0/12 for private use, 192.0.2.0/24 and 198.51.100.0/24 and 203.0.113.0/24 for documentation, 192.168.0.0/16 for private use, 198.18.0.0/15 for benchmarking, 240.0.0.0/4 reserved for future use, and 255.255.255.255 for limited broadcast. The multicast range 224.0.0.0/4 is reserved separately. None of these ranges are used as ordinary globally routable public addresses.

A special-use IP address is an address that has been reserved by the IETF and IANA for a specific technical purpose instead of being assigned for normal public internet use. These reservations are catalogued in the IANA Special-Purpose Address Registry and described in RFC 6890. Categories include private addresses, loopback, link-local, carrier-grade NAT shared space, documentation ranges, benchmarking ranges, multicast, and reserved future-use blocks. Each special-use range has defined properties such as whether it is globally reachable, whether it can be a valid source or destination, and whether routers may forward it.