DNS

Reverse DNS (PTR) Lookup

Resolve IPv4 and IPv6 addresses to their authoritative PTR domain hostnames. Used to verify Forward-Confirmed Reverse DNS (FCrDNS), email sending reputation, and server origin.

Sample IPs:

IPv4 or IPv6 Address

Performs reverse DNS query on in-addr.arpa or ip6.arpa.

How to use

Enter a domain, URL, or value relevant to Reverse DNS (PTR) Lookup.
Run the check and review the output carefully.
Apply recommended fixes, then run the check again to verify.

Common use cases

Pre-deployment validation for Reverse DNS (PTR) Lookup.
Incident triage when security checks fail in production.
Periodic security review as part of technical SEO and hardening.

Example inputs

8.8.8.81.1.1.1142.250.185.46

Common issues and fixes

No PTR record configured

Mail servers (Gmail, Outlook) will often reject inbound SMTP connections from IP addresses lacking a valid reverse DNS PTR record.

Bogon or Private IP

Private RFC 1918 addresses (10.x.x.x, 192.168.x.x, 127.0.0.1) cannot have public DNS PTR resolution.

Recommended remediation

Contact your hosting provider (AWS, DigitalOcean, Hetzner) or ISP to set a custom PTR record matching your mail hostname.

FAQ

Is Reverse DNS (PTR) Lookup free to use?

Yes. This tool is free and can be used without account registration.

Do you store submitted values?

Only the minimum processing needed for the check. For client-side tools, data stays in your browser.

How should I use these results?

Use the output as a diagnostic baseline, apply fixes in your stack, then re-run the check to confirm remediation.

Related security tools

SSL Checker

Live TLS probe: issuer, expiry, SAN, and certificate chain for any domain. Not SSL Labs.

DNS Lookup

Query DNS records (A, AAAA, MX, TXT, NS, CNAME) for any domain using public DNS API.

WHOIS Lookup

Retrieve domain registration details including registrar, registrant, creation date, and expiry.

IP Address Info

Validate IPv4/IPv6. Private, loopback. 100% client-side.

Run a full security check

After this tool passes, run related header and policy checks to catch transport and browser-level risks.

HTTP Header Analyzer HSTS Checker CSP Checker