Free tool
Reverse DNS (PTR) lookup
Resolve PTR records and check forward confirmation.
Free via Google Public DNS — no API key.
Reverse DNS (PTR) maps an IP address back to a hostname. This tool resolves PTR and checks whether that hostname forward-resolves to the same IP — the forward-confirmed reverse DNS pattern mail systems expect.
How to run a PTR lookup
Enter a public IPv4 or IPv6 address. We query public DNS for the PTR in the in-addr.arpa or ip6.arpa tree. If a hostname returns, we attempt A/AAAA confirmation so you can see FCrDNS status at a glance.
Reading the outcome
No PTR is common on residential and some cloud IPs; for mail senders it is a problem. A PTR that points to a generic ISP name may still pass FCrDNS but score weaker than a branded mail hostname. Only the IP owner (usually your VPS/ISP) can set PTR.
- Match PTR hostname to your HELO/EHLO name when possible
- After changes, wait for DNS TTL before re-testing
- Pair with blacklist and SPF/DMARC checks for delivery issues
FAQ
Deeper guide: Read: PTR records and mail