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Execute deep reverse DNS lookups to validate PTR records and confirm Forward-Confirmed reverse DNS (FCrDNS) alignment. Prevent email rejections by verifying your IP resolves to your designated mail server hostname.
A PTR (Pointer) record maps an IP address to a canonical hostname for reverse DNS lookups via the in-addr.arpa (IPv4) or ip6.arpa (IPv6) zone. Receiving MTAs perform a reverse lookup on your sending IP to verify identity. A missing or mismatched PTR record causes spam filter penalization and outright rejections by major providers under RFC 1912 guidelines.
Without a valid PTR record, providers like Gmail and Microsoft 365 reject or heavily penalize your email. It is the baseline trust signal before SPF, DKIM, or DMARC is even evaluated.
Multiple PTR records for a single IP, generic ISP hostname as the PTR target, and IPv6 nibble-boundary formatting errors are the top causes of FCrDNS failures.
Type your sending IP address or mail server hostname into the PTR checker above.
Our engine queries the in-addr.arpa or ip6.arpa zone for your PTR record.
We verify the resolved hostname points back to your original IP bidirectionally.
Contact your ISP to set the correct PTR record and re-run to confirm alignment.
Automatically performs bidirectional DNS checks to ensure Forward-Confirmed reverse DNS, verifying that the IP resolves to a hostname and the hostname resolves back to the same IP, satisfying strict MTA requirements.
Seamlessly handles both IPv4 (in-addr.arpa) and IPv6 (ip6.arpa) address spaces, automatically formatting the IP into the correct reverse nibble boundary format for deep DNS resolution.
Bypasses local DNS caches to query root and authoritative nameservers directly, providing real-time, accurate PTR records and identifying delegation issues in the reverse lookup zone.
Validates FCrDNS by ensuring the A/AAAA records of the resolved hostname match the original querying IP address, closing the authentication loop required by strict MTAs.
Checks PTR record syntax against RFC 1033 and RFC 1912 guidelines, ensuring the target is a fully qualified domain name (FQDN) and not a bare hostname or IP address.
Analyzes the delegation path from the ARPA root down to the specific subnet, ensuring your ISP or hosting provider has correctly delegated control of the reverse zone to your nameservers.
Automate PTR and FCrDNS monitoring across all your sending IPs, get instant alerts on rDNS failures, and receive AI-powered remediation guidance for complex multi-IP infrastructures.