FCrDNS Checker
Forward-Confirmed reverse DNS – checks that a domain's reverse DNS is self-consistent, not just present.
Need to monitor this across every client domain you manage? ActiScan does bulk scanning, scoring, and white-labeled reporting for MSPs.
How to Use the FCrDNS Checker
Enter a domain
Ideally one that sends mail – this matters most for a mail-sending IP.
Click Check
ActiScan resolves the domain's A record(s), reverse-looks-up each IP, then forward-checks the result.
Read the result
Confirmed, present-but-mismatched, or missing entirely – with a plain-English explanation.
What Your Result Means
Forward-confirmedPassAt least one IP's PTR record points to a hostname whose own A record resolves back to that same IP – a complete, self-consistent round trip.
PTR exists, not confirmedWarnA PTR record exists, but the hostname it points to doesn't resolve back to the original IP. Some receiving mail servers treat this the same as having no PTR at all.
No PTR recordWarnNo reverse DNS entry exists for this IP. Matters most if it's sending mail – ask your host or ISP to set one.
What Is FCrDNS?
Forward-Confirmed reverse DNS is a three-hop check: your domain's A record points to an IP; that IP's PTR record points to a hostname; and that hostname's own A record should point right back to the original IP. When all three line up, the reverse DNS story is self-consistent – not just a PTR record that exists, but one that actually confirms itself.
A bare PTR record with no forward confirmation is easy to fake or misconfigure – anyone controlling the reverse zone for an IP block can point it at any hostname they want. The forward round-trip is what makes it meaningful: it requires control of both the reverse zone and the forward zone for the named hostname, which is a much stronger signal.
How to Check FCrDNS Manually
If you'd rather look it up yourself instead of using the checker above:
1. Forward lookup
dig A yourdomain.com +short
2. Reverse lookup that IP
dig -x 203.0.113.10 +short
3. Forward-check the hostname that came back
dig A the-hostname-from-step-2 +short
Confirmed only if this matches the IP from step 1.
Next Steps
Checking email security?
SPF, DKIM, and DMARC are the checks that actually authenticate who can send mail as your domain.
DMARC Checker →Want ongoing monitoring?
ActiScan scans on a schedule and alerts you when something changes.
Start free →Frequently Asked Questions
Is this FCrDNS checker free?
Yes – check any domain for free, no signup required.
What's the difference between this and a plain PTR lookup?
A PTR lookup only confirms a reverse record exists. FCrDNS goes one step further and checks that the hostname it points to actually resolves back to the original IP – the full round trip some receiving mail servers specifically require.
Does this matter for a domain that doesn't send email?
Less so. FCrDNS is mostly relevant for IPs that send mail – it's one signal some receivers weigh against a sending server, alongside SPF/DKIM/DMARC.
Who controls my PTR record?
Whoever owns the IP block – typically your hosting provider or ISP, not your own DNS host. You'll usually need to ask them to set or change it.
My domain has multiple A records – which one does this check?
All of them – the result is a pass if any single IP is forward-confirmed, since that's enough to satisfy most receivers checking the sending IP specifically.