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Reverse DNS Lookup

Find the PTR hostname of up to 20 IP addresses and check forward-confirmed reverse DNS.

What is reverse DNS?

Reverse DNS maps an IP address back to a hostname using a PTR record — the opposite of a normal lookup. Mail servers use it to check that a sending server is legitimate.

What the tool shows

  • The PTR hostname of each IP address (IPv4 and IPv6).
  • The IP addresses that hostname resolves to.
  • Forward-confirmed reverse DNS (FCrDNS) — whether the hostname points back to the same IP.

Why it matters for email

Many receiving mail servers reject or spam-folder messages from IPs without a PTR record, or whose PTR hostname does not resolve back to the IP. A good mail server PTR looks like mail.example.com and matches the server's HELO name.

How to set a PTR record

PTR records are controlled by whoever owns the IP address — your hosting or cloud provider — not by your domain's DNS. Set it in your server provider's control panel or ask their support.

Frequently asked questions

Who controls reverse DNS?

The owner of the IP block, usually your hosting or cloud provider.

Can an IP have more than one PTR record?

Technically yes, but one PTR per IP is strongly recommended, especially for mail servers.

Does reverse DNS affect websites?

Rarely. It mainly matters for mail servers and some security checks.