by hostcloud.ie
Free DNS diagnostics

Reverse DNS Lookup (PTR)

Enter an IP address to find its PTR hostname — the reverse DNS name used by many mail systems and network tools.

About Reverse DNS Lookup (PTR)

Reverse DNS (PTR) maps an IP back to a hostname. Mail providers often expect sending IPs to have valid PTR records that match the HELO/EHLO name. Missing or mismatched reverse DNS is a common delivery problem.

Use this tool with an IPv4 or IPv6 address. After you have the PTR hostname, you can run an A or MX lookup on that name to confirm forward and reverse DNS agree.

Frequently asked questions

What is a PTR record?

A PTR record is reverse DNS: it points from an IP address to a hostname under in-addr.arpa (IPv4) or ip6.arpa (IPv6).

Who sets reverse DNS for my IP?

Usually your ISP, VPS or hosting provider controls PTR records for the IP space they assign you.