🔄 Reverse DNS Lookup
Find the hostname behind any IP, and check it is forward-confirmed.
The phone book, backwards
Normal DNS turns a name into an IP address. Reverse DNS turns an IP address back into a name, using a PTR record stored under a reversed form of the address. It sounds like a curiosity until you run a mail server: receiving servers look up the sending IP's reverse DNS as one of their first spam checks, because legitimate servers almost always have it and throwaway spam setups often do not. This tool shows the PTR hostname for any IPv4 or IPv6 address, then performs the follow-up check that actually matters, forward confirmation: it resolves the hostname and verifies it points back at the same IP. When both directions agree, the address is called forward-confirmed, and that is the configuration receiving servers trust.
Who can fix a missing or wrong record
Not you, usually, and that surprises people. PTR records are controlled by whoever owns the IP address block, which means your hosting company, cloud provider or ISP, not your domain registrar. Most hosts expose it in their control panel as "Reverse DNS" or "PTR record" against the server or IP; on a home connection it is whatever your ISP set, which is one more reason serious mail is not sent from home connections.
Frequently asked questions
Does every IP need reverse DNS?
No. It matters most for mail servers, where its absence genuinely hurts delivery. For a web server it is harmless either way, and most ordinary IPs (home, mobile, office) have a generic provider hostname or none at all, which is completely normal.
What should the PTR hostname be for a mail server?
The server's own hostname, the same name its mail greeting (HELO/EHLO) uses, and that hostname's A record must point back to the same IP. PTR, hostname and greeting all agreeing is the fully consistent setup receivers reward.
Can one IP have several PTR records?
Technically yes, and this tool lists them all, but it is poor practice: forward confirmation can only hold cleanly for the name that resolves back, and mismatched extras confuse exactly the checks you are trying to pass. One IP, one PTR is the rule of thumb.
Why does my cloud server show a generic hostname?
Providers pre-set PTR records to generated names like ip-203-0-113-10.cloudprovider.net. Most let you replace it with your real hostname from the control panel, and for anything sending mail, you should.