Free tool
Reverse DNS (PTR) Lookup Tool
Find the hostname an IPv4 or IPv6 address resolves back to. Looked up via Cloudflare's public resolver, which follows the reverse-zone delegation chain for you.
How this lookup works
A reverse DNS lookup asks "what hostname does this IP address resolve back to?" — the opposite direction of a normal lookup. Reverse-zone delegation boundaries aren't predictable the way domain apexes are, so this always queries through Cloudflare's public resolver, which already follows that delegation chain for you.
Looking up a domain name instead? Try the DNS Lookup tool.