Reverse DNS Lookup
ServerTurn an IP address into its PTR hostname.
How it works
A reverse DNS (PTR) lookup turns an IP address back into a hostname — the opposite of a normal DNS lookup. Mail servers use it to help decide if a sender is legitimate, so a missing PTR record can hurt email deliverability.
Try an example
About the Reverse DNS Lookup
Reverse DNS maps an IP address back to a hostname via a PTR record — the opposite of a normal DNS lookup. This free reverse DNS lookup tool turns any IPv4 or IPv6 address into its PTR hostname, which matters for email deliverability and log analysis.
The lookup runs against live DNS.
How to do a reverse DNS lookup
- Enter an IP address.
- See its PTR (pointer) record hostname, if configured.
- Use it to verify mail servers or identify hosts in your logs.
Why reverse DNS matters for email
The biggest practical use of reverse DNS is email deliverability. Most receiving mail servers do a reverse lookup on the connecting IP and reject or distrust it if there's no PTR record, or if the PTR doesn't match the server's forward hostname. A missing or generic PTR (like an ISP's default) is a common reason legitimate mail lands in spam.
Frequently asked questions
What is reverse DNS (rDNS)?
Reverse DNS resolves an IP address to a hostname using a PTR record, the reverse of forward DNS which resolves a hostname to an IP.
Why does reverse DNS matter for email?
Many mail servers reject or distrust senders whose IP has no matching PTR record, so proper rDNS improves email deliverability.
Why is there no PTR record?
Reverse DNS is optional and set by whoever controls the IP block. If no PTR is configured, the lookup returns nothing.
Why is there no PTR record for an IP?
Reverse DNS is optional and controlled by whoever owns the IP block — usually the hosting provider or ISP, not you. If they haven't set a PTR, the lookup returns nothing. For a mail server you often have to request the PTR from your provider.