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Reverse DNS Lookup - PTR Record Check
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Reverse DNS (PTR) Lookup
Perform reverse DNS lookup on any IPv4 or IPv6 address to find the associated PTR record. Verifies forward-confirmed reverse DNS (FCrDNS) by checking if the PTR hostname resolves back to the original IP. Identifies hosting providers from PTR patterns. Reverse DNS is critical for email deliverability and IP reputation assessment.
How It Works
The IP address is converted to the in-addr.arpa (IPv4) or ip6.arpa (IPv6) format and a PTR query is performed. If a PTR record exists, the tool then performs a forward lookup on the returned hostname to verify it resolves back to the original IP (FCrDNS check). Known hosting provider patterns in PTR hostnames are identified automatically.
FAQ
What is reverse DNS used for?
Reverse DNS maps an IP address to a hostname. Email servers check reverse DNS to verify sender legitimacy — many reject mail from IPs without a valid PTR record. It's also used in security logging, access control, and network troubleshooting.
What is forward-confirmed reverse DNS (FCrDNS)?
FCrDNS means the PTR record's hostname resolves back to the original IP via an A/AAAA lookup. If IP 1.2.3.4 has PTR "mail.example.com" and mail.example.com resolves to 1.2.3.4, that's FCrDNS confirmed. This prevents spoofed PTR records.
How do I set up a PTR record?
PTR records are managed by the IP address owner (usually your hosting provider or ISP), not your DNS registrar. Contact your provider to set the PTR record for your server IP. For cloud providers like AWS/GCP/Azure, use their reverse DNS configuration in the console.
PTR Record
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Tool Features
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Related Guides
Coming Soon Bulk reverse DNS scanning — coming soon.