Reverse DNS (PTR)
Find the hostname an IP address resolves back to.
The domain to look up
How this lookup works
Forward DNS turns a name into an address; reverse DNS does the opposite, using a PTR record. Enter an IP and this tool queries the PTR record that its owner has published, if any.
What the results mean
- PTR hostname
- The name the address’s owner has assigned to it. For a mail server this usually matches its forward record, which receiving servers check.
- No PTR record
- The address has no reverse record. Common for home and mobile connections, and not a problem unless the address is being used to send mail.
Common problems and fixes
- Mail from my server is being rejected for a missing PTR
- Set it with whoever owns the IP address, which is your hosting provider or ISP rather than your DNS host — reverse DNS is delegated with the address block, not the domain. Most providers expose it in their control panel. It also needs to match: the PTR should resolve forward to the same address.
- The PTR exists but mail is still distrusted
- Check that it matches in both directions. Receivers commonly verify that the hostname in the PTR resolves back to the same IP, and a mismatch is treated as worse than no record at all. Also confirm the name looks like a mail server rather than a generic provider-assigned hostname.
- A home connection has no PTR record
- That is normal and nothing to fix. Consumer address ranges typically carry a generic PTR or none, because they are not meant to originate mail. If you are trying to send mail from one, reverse DNS is the least of the obstacles — most providers block outbound port 25 from residential ranges entirely.
Frequently asked questions
Why does reverse DNS matter for email?
Receiving mail servers often reject or distrust mail from an address whose PTR record is missing or does not match its forward hostname. It is a basic signal of a legitimately-run mail server, which is why hosting providers let you set it.
Can I set the reverse record for my home IP?
Usually not — it is controlled by your ISP, who owns the address. On a server or hosting account you typically can, through the provider’s control panel.
Why is reverse DNS controlled by the address owner?
Because reverse lookups resolve through a special zone derived from the address itself, and authority over that zone follows the allocation of the address block. Anyone could claim a name points at an address; only the party who holds the address can say what that address is called, which is what makes the check meaningful.
Can one IP have several PTR records?
Technically yes, and it is a bad idea. Multiple PTRs make the answer ambiguous, and software checking the record may pick any of them or treat the result as a failure. One address, one name — with as many forward names pointing at that address as you like.
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