Free · without registration
Resolve IP address by Reverse DNS
Find the PTR host name of a public IP address. The checker also checks whether the found name leads back to the original IP via A or AAAA.
Start of test
Their results
Differentiate forward and backward resolution
A normal DNS query translates a hostname into an IP address. Reverse DNS asks for a PTR entry in the opposite direction. For IPv4, the in-addr.arpa zone is used, for IPv6 the ip6.arpa zone. The tool creates the appropriate query name and supports both address families.
Why Backward Comparison is Useful
A PTR name can exist without its A or AAAA record pointing to the original IP. The checker therefore compares up to five found PTR targets with the forward resolution. For IPv6, the actual address counts, not the spelling with differently shortened zero blocks. DNS errors are reported separately from a confirmed missing reference back.
Change PTR to the right provider
The reverse zone is normally the responsibility of the provider of the IP network. An additional A-record at the domain provider therefore does not generate a PTR entry. In the hosting panel, check the reverse DNS setting or ask the server provider. For shared IPs, the PTR can show a general hosting name and does not have to name every website operated on it.
Importance for mail servers and websites
A consistent reverse DNS entry is especially relevant when administering mail servers. However, it proves neither domain ownership nor a good broadcaster reputation. For ordinary websites, a lack of their own PTR is not a blanket SEO error. Private, local and reserved addresses are excluded for this public examination.
Example of classification
192.0.2.10 is used only as a documentation example. For a real public IP, a matching PTR points to mail.example.org; its A-record should contain the same IP for consistent back-testing.
Frequent questions
Who can put my PTR entry?
Usually the provider that manages the IP address or reverse zone.
Why does the IP not show my website domain?
Multiple websites can use the same IP. The PTR may contain a general server name.
Does the Checker support IPv6?
Yes. It creates the ip6.arpa query and compares the target with AAAA records.