Reverse DNS (PTR)

What this tool does

Reverse DNS works the opposite way from regular DNS: instead of turning a name into an IP, it finds the name associated with an IP through the PTR record. The tool also checks whether that name points back to the same IP, known as forward-confirmed reverse DNS (FCrDNS).

Why it matters

Mail servers check the reverse DNS of whoever sends them messages. A server with no PTR, or with a PTR that doesn't match, is very likely to have its email rejected or sent to spam. For regular web servers the PTR is optional, but it helps identify them in logs and traceroutes.

How to set it up

The PTR is not in your domain's DNS zone. It is set by whoever owns the IP block: your VPS or dedicated server provider. There is usually a "Reverse DNS" or "rDNS" field in the control panel. Set the PTR to the server's name, such as mail.yourdomain.com, and create an A record for that name in your DNS pointing to the same IP.

Frequently asked questions

What is a PTR record?

It is the record that maps an IP address to a name. It is used for reverse DNS and is set by the owner of the IP block.

How do I set up reverse DNS?

In your server provider's control panel, look for Reverse DNS or rDNS. If there isn't one, ask support. The chosen name must have an A record pointing to the same IP.

Do home connections have reverse DNS?

Yes, but it is a generic name created by the ISP. Mail servers usually reject email sent directly from home connections.

What is FCrDNS?

It is the confirmation that the PTR name resolves back to the same IP. Many mail servers require it.