Reverse DNS Lookup
Find the PTR record for an IP address and check that it resolves back.
Reverse DNS maps an IP address back to a hostname through a PTR record in the in-addr.arpa or ip6.arpa zone. The PTR is published by whoever controls the address block — usually the ISP or hosting provider — not by the owner of the hostname.
Because anyone with a block can publish any name, a PTR alone proves little. Forward-confirmed reverse DNS (FCrDNS) checks that the hostname resolves back to the same address. Mail servers and many anti-abuse systems rely on that check.
Frequently asked questions
Why doesn't my IP have a PTR record?
Many residential and mobile ranges have no reverse DNS, or a generic one. Only the holder of the address block — your ISP or hosting provider — can set it.
How do I change the reverse DNS of my server?
In your hosting or cloud provider's control panel (often under networking or rDNS). Set a hostname that also resolves forward to the same IP.
Can an IP have more than one PTR record?
It's technically allowed, but most software only uses the first one; publishing a single PTR is recommended.