🔄 Reverse DNS Lookup
Resolve any IPv4 or IPv6 address to its hostname via PTR record (rDNS).
About Reverse DNS Lookup
Reverse DNS (rDNS) resolves an IP address back to a hostname using a PTR record. While a forward DNS lookup maps a name to an IP, a reverse lookup asks "what hostname is registered for this IP?". PTR records are stored in special zones: in-addr.arpa for IPv4 (octets reversed) and ip6.arpa for IPv6 (nibble by nibble reversed). Both IPv4 and IPv6 are fully supported — enter any address in standard notation.
Reverse DNS is widely used in email delivery — many mail servers reject messages from IPs without a matching PTR record as a basic anti-spam measure. It also appears in server logs, monitoring dashboards, and security tools to display readable hostnames instead of raw IPs. PTR records are set by whoever controls the IP address block (your hosting provider or ISP), not by the domain owner — contact your provider to set or update one.
Not all IPs have a PTR record, and that is normal: most cloud VMs, CDN edge nodes, and consumer broadband IPs have no reverse DNS by default. If you need the organization behind an IP rather than a hostname, the IP Location tool provides ISP, ASN, and geolocation data instead.