Reverse DNS Lookup

Find the hostname associated with an IP address via PTR record.

Reverse DNS lookup resolves IP addresses back to hostnames using PTR records. Unlike standard DNS that maps names to IPs, reverse DNS identifies which domain is associated with a given IP address.

Result

Enter an IP to look up its hostname.
In Action

Reverse DNS in action

Your server log shows repeated login attempts from an unfamiliar IP. Run a reverse DNS lookup on it: a PTR record often reveals the hosting provider (e.g. "crawl-66-249.amazonaws.com"), telling you instantly whether it is a search engine bot or an attacker to block.

Frequently Asked Questions

What is a reverse DNS lookup?

A reverse DNS lookup finds the hostname associated with an IP address.

How do I do a reverse DNS lookup online?

Enter an IP address and run the lookup — the PTR record shows which hostname is registered for that IP. This is the standard way to identify the owner or purpose of an IP address you see in server logs.

Why do so many IPs have no PTR record?

PTR records are optional, and many providers (especially residential and cloud providers) do not create them. Missing PTR is not an error — but mail servers often reject email from IPs without PTR records as an anti-spam measure.

What is the difference between forward and reverse DNS?

Forward DNS maps a name to an IP (example.com -> 1.2.3.4). Reverse DNS maps an IP to a name (1.2.3.4 -> host.example.com) using PTR records. Most troubleshooting uses forward DNS; log analysis and email reputation use reverse DNS.