About this tool
Enter an IPv4 address to see its classful class (A–E), whether it is private, loopback, link-local or public, and the default mask for its class. It runs entirely in your browser.
Frequently asked questions
What are private addresses?
RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 for private networks that are not routed on the public internet.
What is a link-local address?
The 169.254.0.0/16 block is self-assigned when no DHCP server is available, allowing local communication on a single link.