Reverse DNS Lookup: PTR & Forward Match
Follow an IPv4 or IPv6 address to its PTR name and back. Find the mismatch, compare a fix and copy a request for the right DNS operator. Free, no sign-up.
- IP → PTR → A / AAAA
- Copy repair request
- Check a short IP list
One check follows the IP to its PTR names and back. No connection is made to the target IP.
Only public DNS is checked. For mail, enter the actual sending IP; MX records identify receiving servers and may be different. SMTP banners, reputation and delivery are not tested.
At most four distinct valid PTR names are checked per IP. Additional names remain unchecked.
The result is kept in memory for up to 30 minutes, until you leave or reload this page.
Addresses and names are hidden by default. Enable the option to include them. Reports are copied locally and are not sent to a provider.
Check a short IP list
PTR record missing or forward DNS does not match?
Run the combined check to see which part needs attention. PTR changes normally belong with the IP provider; A and AAAA changes belong with the hostname’s DNS operator.
Does this check IPv6 reverse DNS for a mail server?
Yes. Enter the actual IPv6 sending address to check its PTR and the hostname’s AAAA records. A working IPv4 check does not establish that IPv6 is configured correctly.
How to use this tool
- Enter the actual public IP to check. For mail, use the sending server’s IP. Add an expected hostname if you have one.
- Run the combined PTR and forward check. Review both resolver paths and the suggested next step.
- Keep a result before changing DNS, then check again. Copy a repair request or export the report with or without addresses.
Read the result
Reverse DNS maps an IP address to a PTR name in in-addr.arpa or ip6.arpa. The address-space operator normally controls the reverse zone; publishing a website A record does not automatically create PTR. Resolver caches can return different answers while records change. An optional forward check asks whether the PTR hostname has an A or AAAA answer containing the original IP. A matching pair is useful for troubleshooting but does not establish identity, reputation or successful mail authentication.
Why is there no PTR record?
The address owner may not have published one, or a resolver may return an empty answer or NXDOMAIN. A timeout or resolver error is shown as unavailable, not as proof that PTR is absent.
Does a forward match prove that a server is safe?
No. It shows consistency between a PTR name and an A or AAAA response at the time checked. It does not verify ownership, certificates, SPF, DKIM, DMARC or the content hosted there.
Can I check a private IP?
Its reverse name can be generated locally, but public DNS is not queried for private or reserved addresses. Internal PTR records must be checked through your own network resolver.