Reverse DNS Lookup (PTR)
Find the hostname behind any IPv4 or IPv6 address using its PTR record.
Free • no sign-up • results run live in your browser via public DNS resolvers.
What is a reverse DNS (PTR) lookup?
A normal DNS lookup turns a hostname like example.com into an IP address. A reverse DNS lookup does the opposite: it takes an IP address and finds the hostname associated with it, using a special record type called a PTR record.
PTR records live in the in-addr.arpa (IPv4) and ip6.arpa (IPv6) zones. Reverse DNS is most important for email servers: many mail providers reject or flag messages from IP addresses that don't have a valid PTR record matching their forward DNS.
When you need reverse DNS
- Email deliverability — your sending IP should have a PTR record that matches its hostname.
- Server logs & security — identifying which host an IP belongs to.
- Troubleshooting — confirming an IP resolves back to the expected name.
Frequently asked questions
Reverse DNS must be configured by whoever controls the IP address — usually your hosting provider or ISP, not your domain registrar. If there's no PTR record, ask your provider to add one.
For mail servers, yes — best practice is “full circle” DNS: the IP's PTR points to a hostname, and that hostname's A/AAAA record points back to the same IP.
Technically yes, but it's discouraged. Most mail systems expect a single, authoritative PTR record per IP.