Reverse DNS Lookup
Find the hostname associated with an IP address via PTR records.
Reverse DNS (rDNS) resolves an IP address to a hostname using PTR records. It's the opposite of standard DNS resolution and is critical for email server validation, security logging, and network diagnostics.
Forward-Confirmed reverse DNS (FCrDNS) validates that a PTR record's hostname resolves back to the original IP. This is required by most major email providers (Gmail, Outlook, Yahoo) for proper email delivery.
How to Use This Tool
- What to Enter
- Enter an IP address or domain to perform a reverse DNS lookup and find the associated PTR record.
- What You Get
- Shows the PTR record hostname, forward-confirmed reverse DNS (FCrDNS) status, and whether the forward and reverse records match.
How to Interpret Results
A matching PTR record (forward-confirmed rDNS) means the IP resolves to a hostname that resolves back to the same IP. This is critical for email servers — many mail providers reject email from IPs without valid rDNS. Missing PTR records may indicate residential IPs or misconfigured servers.
Common Issues & Troubleshooting
Missing PTR records cause email deliverability problems. ISPs control rDNS for their IP ranges, so you may need to request PTR record creation from your hosting provider. Generic rDNS (like 123-45-67-89.isp.net) is less trustworthy than custom hostnames.