Reverse DNS (PTR Lookup)
Look up PTR records for an IP address and see the associated hostnames.
About the Reverse DNS (PTR Lookup)
Reverse DNS maps an IP address to one or more hostnames using PTR records in the in-addr.arpa (IPv4) or ip6.arpa (IPv6) zones. Mail servers, security tools, and log analysis often show IPs first; a PTR lookup tells you what name is officially associated with that address.
Enter an IPv4 or IPv6 address and the tool queries public DNS for PTR records. When hostnames are returned, it also runs a quick forward lookup (A and AAAA) on each name so you can see whether the reverse and forward records agree. Mismatched forward and reverse DNS is a common cause of mail delivery issues.
The lookup runs on our server over DNS-over-HTTPS, the same approach as the other Email and DNS tools. The IP you enter is sent to our server and is not stored. No third-party lookup API is involved.
PTR records are optional. Many IPs legitimately have no reverse DNS. Absence of a PTR is not always a problem, but receiving mail servers often expect one that matches the sending hostname.
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Frequently asked questions
What is reverse DNS used for?
It maps an IP to hostnames via PTR records. Mail providers use it to verify that a sending server's IP matches its claimed hostname. Logs and dashboards also use it to show readable names instead of raw IPs.
Why is forward confirmation shown?
A healthy setup has PTR pointing to a hostname that forward-resolves back to the same IP. If forward DNS returns different addresses, the reverse record may be stale or misconfigured.
Does this work for IPv6?
Yes. IPv6 PTR records live under ip6.arpa. Enter a full or compressed IPv6 address and the tool builds the correct query name.
Is my IP address stored?
No. Our server queries public DNS and returns the result. The IP is not logged or persisted.
No PTR records were found. Is that an error?
Not necessarily. PTR is optional for many services. For outbound mail, however, you should configure PTR with your hosting or ISP provider so it matches your mail server hostname.