Reverse DNS Lookup

Look up the hostname associated with any IP address using reverse DNS (PTR records). Identify servers, CDNs, and mail providers by IP. Free tool.

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Reverse DNS Lookup queries PTR records to find the hostname associated with any IP address. Useful for identifying mail servers (important for spam filtering), CDN nodes, cloud provider ranges, and verifying forward-confirmed reverse DNS (FCrDNS) for email deliverability.

How it works

  1. 1Enter the IP address you want to look up
  2. 2Click Lookup
  3. 3View the PTR hostname(s) associated with the IP
  4. 4See forward DNS confirmation status

Who uses this tool

  • ✓Email admins setting up PTR records for mail deliverability
  • ✓Network engineers identifying unknown IP addresses
  • ✓Security analysts investigating suspicious traffic sources
  • ✓Hosting customers verifying their server's rDNS entry
  • ✓Spam filter operators checking sender IP reputation

Frequently Asked Questions

What is reverse DNS?
Reverse DNS (rDNS) maps an IP address back to a hostname using PTR records, the reverse of normal DNS which maps hostnames to IPs.
Why is rDNS important for email?
Many mail servers reject email from IPs with no PTR record. Setting up a matching PTR record improves deliverability.
What is FCrDNS?
Forward-Confirmed Reverse DNS means the PTR hostname also resolves back to the same IP. It's a strong signal of legitimate mail infrastructure.

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