Reverse DNS (PTR) Lookup
Free reverse DNS lookup. Check the PTR record for any IP and verify forward-confirmed reverse DNS (FCrDNS) - the check Gmail and Microsoft run on sending IPs.
About the Reverse DNS (PTR) Lookup
This free reverse DNS lookup checks the PTR record for any IPv4 or IPv6 address and verifies forward-confirmed reverse DNS (FCrDNS) - that the PTR hostname resolves back to the same IP. Gmail, Microsoft and most receivers run this exact check on every sending IP.
A sending IP without valid reverse DNS is rejected or heavily penalised. Enter an IP to see its PTR record and whether FCrDNS passes.
Frequently asked questions
What is reverse DNS (PTR)?
Reverse DNS maps an IP address back to a hostname via a PTR record. Mail receivers check that sending IPs have a PTR record and that it forward-confirms to the same IP.
What is FCrDNS?
Forward-confirmed reverse DNS means the PTR hostname of an IP resolves back to that same IP. Receivers require this for sending IPs; a mismatch or missing PTR hurts deliverability.
How do I set reverse DNS?
PTR records are set by whoever controls the IP - usually your hosting or mail provider. Ask them to point the PTR to your mail server hostname, and ensure that hostname's A record points back to the IP.
Did this check reveal a problem?
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