What is an IP Lookup (Reverse DNS)?
Reverse DNS maps an IP back to a hostname via its PTR record: the quickest way to identify whose server an IP in your logs belongs to, and a requirement for mail servers to be trusted.
Enter any public IPv4 or IPv6 address and get its PTR names from a live lookup.
Frequently asked questions
Why does my IP have no PTR record?
PTR records are set by whoever controls the IP block: typically your hosting provider. Many consumer and cloud IPs simply have none until configured.
Why does PTR matter for email?
Receiving mail servers check that your sending IP has a PTR matching your mail hostname: missing or generic PTRs increase spam scoring.
Does PTR prove who owns an IP?
It is set by the IP holder, so it is informative but not cryptographic proof. Combine with WHOIS for ownership.
Does this work for IPv6?
Yes: both address families are supported.