Reverse DNS lookup.
Enter an IP address to find the hostname it points to (its PTR record). Enter a domain and we'll look up its IP addresses first. We also check that the hostname points back to the same IP, which mail servers use to judge whether to trust a sender.
- Free, no sign-up
- We check public information only. How your data is handled
How to use the reverse DNS Lookup
- Enter an IPv4 or IPv6 address, or a domain name.
- We look up the PTR record for each address.
- Check "Forward-confirmed": the hostname should point back to the same IP.
- If you run a mail server and the PTR is missing or wrong, ask your hosting provider to set it.
What reverse DNS is
Normal DNS turns a name into an IP address. Reverse DNS does the opposite: it turns an IP address into a name, using a PTR record. The PTR record is controlled by whoever owns the IP address, usually your hosting or internet provider, not by your domain's DNS settings.
Why it matters for email
Many mail servers check the reverse DNS of every server that sends them mail. If the IP has no PTR record, or the hostname doesn't point back to the same IP (forward-confirmed reverse DNS, or FCrDNS), the mail is more likely to be rejected or marked as spam. Gmail requires valid reverse DNS for anyone sending to its users.
If your email goes through Google Workspace, Microsoft 365 or another provider, they handle this. It matters when your own server or hosting account sends mail directly, for example from a website contact form.
Other uses
- Seeing which company or hosting provider an IP address belongs to.
- Checking what a server identifies itself as.
- Making sense of IP addresses in server logs.
Related checks
For mail problems, also run the email blacklist checker and the SPF, DKIM and DMARC checker. To see all of a domain's records, use the DNS lookup.
About the reverse DNS Lookup.
How do I set a PTR record?
Ask whoever owns the IP address, usually your hosting or server provider. Some, like most VPS providers, let you set it in their control panel. You can't set it in your domain's DNS zone.
What is forward-confirmed reverse DNS?
When an IP's PTR hostname, looked up normally, points back to the same IP. Mail servers treat this as a sign the sender is set up properly.
Why does my IP have no reverse DNS?
Many home and shared hosting IPs have no PTR record, or a generic one. It only matters if that IP sends email directly.
Does reverse DNS affect SEO?
No. It matters for email delivery and server identification, not search rankings.
Can I look up private IP addresses?
No. Private addresses like 192.168.x.x have no public reverse DNS, and we don't query them.
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