Free Reverse DNS Lookup
Find the hostname behind an IP address.
What is the Reverse DNS Lookup?
Normal DNS turns a name into an address; reverse DNS does the opposite, turning an IP back into a hostname. It's easy to overlook until email starts landing in spam — because mail servers quietly check the reverse record of whatever's connecting to them, and a missing or mismatched one is a red flag.
This reverse DNS lookup finds the hostname behind an IP and tells you whether it forward-confirms, so you can spot the mismatches that hurt deliverability.
Last updated: Aug 13, 2026
What does this tool do?
You enter an IPv4 or IPv6 address and the tool queries its PTR (pointer) record to find the hostname it maps to.
It then resolves that hostname forward and checks whether it points back to the same IP, marking each result as forward-confirmed or not.
Key features
PTR lookup
Finds the hostname an IP maps to.
IPv4 & IPv6
Works with both address families.
Forward-confirm
Checks the hostname resolves back to the IP.
Clear verdict
Marks matches and mismatches.
No-record handling
Tells you when no PTR is set.
Example
Common use cases
- Email admins — Ensure sending IPs have matching reverse DNS.
- DevOps — Verify PTR records after provisioning servers.
- Security analysts — Identify the host behind an IP in logs.
- Sysadmins — Debug mail-delivery and trust issues.
- Network engineers — Confirm rDNS matches forward DNS.
- Hosting customers — Request PTR setup from a provider.
- Analysts — Resolve IPs found in analytics or logs.
- Anyone reading server logs — Put a name to an address.
Benefits
- It reveals the hostname behind any public IP.
- It flags reverse/forward mismatches that hurt email.
- It handles both IPv4 and IPv6.
- It tells you clearly when no PTR record exists.
Tips
- Set a PTR record for every IP that sends email.
- Make reverse and forward DNS match (forward-confirmed rDNS).
- PTR records are usually set by whoever controls the IP — often your host.
- Use a hostname that reflects your domain, not a generic provider name.
- Check rDNS if your mail is landing in spam.
- IPv6 senders need PTR records too.
- Remember DNS changes take time to propagate.
- Re-check after moving servers or changing IPs.
Common mistakes to avoid
No PTR record on a mail server
Fix: Ask your host to add a PTR record for the sending IP.
Reverse and forward DNS don't match
Fix: Make the hostname resolve back to the same IP (forward-confirmed rDNS).
Generic provider hostname
Fix: Use a PTR that reflects your own domain where possible.
Forgetting IPv6
Fix: Set PTR records for IPv6 addresses that send mail too.
How it works
- 1
Enter an IP
Any public IPv4 or IPv6 address.
- 2
Look up
It queries the PTR record for the IP.
- 3
Review
See the hostname and whether it forward-confirms.
Frequently asked questions
A PTR record maps an IP address back to a hostname — the opposite of a normal A/AAAA lookup. It's widely used by mail servers to check senders.
That the hostname the IP points to also resolves back to that same IP (matching forward and reverse DNS), a trust signal mail servers rely on.
A PTR record that maps an IP address back to a hostname — the opposite of a normal A/AAAA lookup.
That the hostname the IP points to also resolves back to that IP, matching forward and reverse DNS — a signal mail servers trust.
Receiving mail servers check the sending IP's PTR record; a missing or mismatched one increases the chance your mail is flagged as spam.
Whoever controls the IP block — usually your hosting provider or ISP, not your domain registrar.
Many IPs simply don't have one set. For mail servers, that's worth fixing with your provider.
No. The lookup runs live and nothing is saved.
Conclusion
A reverse DNS lookup puts a name to an IP and confirms it matches — essential for email deliverability and log analysis. Pair it with the DNS records checker and email verifier to keep your mail setup trusted.