Free tool
Reverse DNS (PTR) Lookup
Find the PTR record for a sending IP and confirm forward-confirmed reverse DNS, the check Gmail and Yahoo run on every connection.
What the reverse dns lookup does
A reverse DNS lookup finds the hostname a PTR record assigns to an IP address. For email, the PTR must also resolve back to the same IP, called forward-confirmed reverse DNS. Mailbox providers check it on every connection. This tool looks up the PTR for any IPv4 or IPv6 address or mail server hostname, confirms the forward match and flags generic names.
How it works
How the Reverse DNS Lookup works
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Enter an IP or host
Paste a sending IP, or a mail server hostname and we check each of its IPs.
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PTR and forward check
We look up the PTR, then resolve that hostname to confirm it points back to the IP.
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Pass or fix
Missing records, mismatches and generic names are flagged with the fix.
Reading your result
What the result means
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Forward-confirmed
One PTR that resolves back to the IP. Exactly what receivers want to see.
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Generic or multiple PTRs
Works, but a generic or duplicated name looks unmanaged. Use mail.yourdomain.
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Missing or mismatched
No PTR, or one that does not resolve back. Expect rejections at Gmail and Yahoo.
FAQ
Reverse DNS FAQ
What is a PTR record?
A PTR record maps an IP address back to a hostname, the reverse of an A record. It lives in the in-addr.arpa zone for IPv4 or ip6.arpa for IPv6, which the owner of the IP block controls.
What is forward-confirmed reverse DNS?
The PTR hostname for an IP must itself resolve back to that same IP. Mailbox providers check this match to tell managed mail servers from compromised machines. A PTR that does not resolve back fails the check.
Who sets the PTR record for my server?
Whoever owns the IP: your hosting company, cloud provider or ISP. Most hosting control panels have a reverse DNS field. Set it to a hostname on your own domain and add a matching A record.
Do Gmail and Yahoo require reverse DNS?
Yes. Google requires sending domains or IPs to have valid forward and reverse DNS, and Yahoo requires a valid PTR. Mail from IPs without it is often rejected or sent to spam.
Should the PTR match my HELO name?
It should. The cleanest setup uses one hostname, such as mail.example.com, as the PTR, the HELO or EHLO name and an A record pointing to the IP.
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Clean a list
Clean infrastructure deserves a clean list
Our own verification IPs pass forward-confirmed reverse DNS before they carry a single probe. Verify your list on infrastructure built the right way.
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