Reverse DNS lookup.
Look up an IP address's PTR record — the hostname it reverses to — and find out whether that hostname points back to the same IP (forward-confirmed rDNS). Enter any IPv4 or IPv6 address; the check runs against live DNS. No account, no card.
Enter an IPv4 or IPv6 address. We resolve its PTR record — the hostname the IP reverses to — and check whether that hostname points back to the same IP (forward-confirmed rDNS).
What a reverse DNS lookup tells you
A PTR record maps an IP address back to a hostname. For anyone sending email, the lookup answers two practical questions:
- Does this IP have reverse DNS at all?
- A sending IP with no PTR record is a red flag to receiving mail servers — many defer or reject it outright. This is the fastest way to catch a missing PTR before it costs you the inbox.
- Is the rDNS forward-confirmed?
- The tool re-resolves each PTR hostname and checks it points back to the queried IP. Matching in both directions (FCrDNS) is the trusted setup mailbox providers look for from bulk senders.
Why it matters for sending mail
Reverse DNS is one of the cheapest reputation signals to get right, and one of the most common to overlook. Some blocklists reject purely on it — SpamRats keeps a list dedicated to IPs with missing or generic PTR records, and mail from a listed IP can be blocked before it's even read. It's also step zero when you bring a new sending IP online: set a forward-confirmed PTR before you start warming up the domain and IP, so every message counts toward the reputation you're building rather than against it.
Reverse DNS lookup — FAQ
Reverse DNS set — now send to a clean list
A forward-confirmed PTR protects your sender reputation; verifying your list keeps bounces and spam traps from undoing that work. Start free with 100 credits, no card required.