Reverse DNS Lookup
Find the hostname behind an IP address.
How to use the reverse DNS lookup
- Enter an IPv4 or IPv6 address, or leave the field empty to use your own.
- Press Find hostname.
- The result shows the PTR record, the hostname and whether that hostname points back to the same address.
What forward-confirmed means
A reverse DNS record (PTR) maps an IP address to a hostname. Anyone who controls the address block can set any name, so mail servers also check the other direction: the hostname must resolve back to the same IP. When both match, the address has forward-confirmed reverse DNS (FCrDNS).
| Result | Meaning |
|---|---|
| Forward-confirmed | The PTR hostname resolves back to this IP. Mail servers accept it as valid. |
| Does not resolve back | The hostname exists but points somewhere else. Mail from this IP may be treated as suspicious. |
| No reverse DNS | The address has no PTR record. Many mail servers reject mail from such addresses. |
How reverse DNS works
For IPv4, the address is reversed and placed under the special domain in-addr.arpa. The PTR record for 8.8.4.4 lives at 4.4.8.8.in-addr.arpa. IPv6 addresses use each hexadecimal digit, reversed, under ip6.arpa.
Only the owner of the address block (your hosting provider or ISP) can set the PTR record, not the owner of the domain. If you run a mail server, ask your provider to set a PTR record that matches your mail server's hostname.
Learn more in what is reverse DNS.
Frequently asked questions
Why does my home IP have a strange hostname?
Internet providers give every customer address a generated name that often contains the IP and the region, such as host81-2-69-160.example-isp.net. It is normal.
Can I set the reverse DNS for my own domain?
Only for IP addresses you control. Hosting providers usually let you set the PTR record of your server in their control panel.
Does reverse DNS reveal who uses an IP?
Rarely. It names the provider or the server, not the person using the connection.
Learn more
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