Reverse DNS Lookup
Enter an IPv4 or IPv6 address to look up its PTR (reverse DNS) record.
About this tool
This tool constructs the correct in-addr.arpa (IPv4) or ip6.arpa (IPv6) query name for the address you provide and performs a PTR lookup over DNS-over-HTTPS. If the result is more than one hostname, all are shown.
How to use this tool
- Enter an IPv4 or IPv6 address, e.g.
1.1.1.1. - Select "Look up". The URL updates with your query, so results can be bookmarked or shared.
Frequently asked questions
What is reverse DNS?
Reverse DNS resolves an IP address back to a hostname, using specially-formatted PTR records under in-addr.arpa (IPv4) or ip6.arpa (IPv6). It is the opposite of a normal ("forward") DNS lookup, which resolves a hostname to an IP address.
Why does an IP address have no PTR record?
A PTR record must be configured by whoever controls that IP address's reverse DNS zone — usually the hosting provider or ISP. Many IP addresses, particularly residential ones, have no PTR record configured at all, which is normal.
What is reverse DNS commonly used for?
Mail servers often check reverse DNS as part of spam filtering (a mismatch between forward and reverse DNS is a common spam signal). It is also useful for identifying the organisation behind an IP address seen in logs.
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