Reverse DNS lookup
Reverse DNS maps an IP address back to a host name using a PTR record. Enter an IPv4 or IPv6 address and the lookup builds the special reverse name for you, queries it, and compares answers from two public resolvers.
- Free, no subscription
- No account
- Part of the DNS Lookup
What it checks
- The PTR record for IPv4 and IPv6 addresses.
- The in-addr.arpa or ip6.arpa name, built automatically.
- Answers from Cloudflare and Google side by side.
- NXDOMAIN when no reverse record exists.
Why reverse DNS matters for email
Many receiving mail servers check that the IP address sending to them has a PTR record, and that the name it points to resolves back to the same address. A mail server without matching reverse DNS is far more likely to have its messages rejected or marked as spam. Most other services don't depend on reverse DNS, but logs and diagnostic tools read it.
Who controls the PTR record
Reverse DNS belongs to whoever owns the IP address block, usually your hosting provider, cloud platform or internet provider, not the company that hosts your domain's DNS. To set or change a PTR record, use your provider's control panel or ask their support. For IPv6, the reverse name has one label for every hex digit of the address, which is why the tool builds it for you.
Frequently asked questions
What is a PTR record?
A DNS record that maps an IP address to a host name: the reverse of an A or AAAA record.
Why can't I set a PTR record in my DNS panel?
Reverse records are managed by the owner of the IP address block. Ask your hosting or cloud provider to set it.
Do I need reverse DNS for a mail server?
Yes. Receivers commonly expect a PTR record that matches the server's host name, and reject or flag mail without one.
Does it support IPv6?
Yes. Enter any IPv6 address, including shortened forms, and the tool builds the full ip6.arpa name.
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