Reverse DNS Lookup
Enter an IP address to find its hostname (the PTR record), then check that the hostname points back to the same IP. Mail servers look for exactly this before they trust a sender.
What reverse DNS is
Normal DNS turns a name into an IP address. Reverse DNS goes the other way: it turns an IP address into a name, using a special PTR record stored under in-addr.arpa (or ip6.arpa for IPv6). The result shows that name so you can see exactly what was asked.
The important part is who controls it. PTR records are set by whoever owns the IP address, which is usually your hosting provider or internet provider, not your DNS provider. If you need to change one, look for a "reverse DNS" or "rDNS" setting in your VPS control panel, or ask your provider's support.
Why mail servers care
If you run your own mail server, receiving servers check two things about your sending IP:
- It has a PTR record.
- The hostname in that record resolves back to the same IP. This is called forward-confirmed reverse DNS.
Missing or mismatched reverse DNS is a common reason for mail from a new VPS being rejected or sent to spam. Generic names such as 203-0-113-10.dynamic.example.net also look like home connections and are often treated with suspicion. Set the PTR to a real hostname like mail.yourdomain.com, and give that hostname an A record pointing to the same IP.
Limitations
- Many IP addresses, especially home connections and cloud ranges that nobody configured, have no PTR record. That is normal unless the IP sends email.
- An IP can have more than one PTR record. That is allowed but confuses some mail servers; one is best.
Questions
Do I need reverse DNS for a website?
No. Browsers never check it. It only matters for sending email, and for some logs and security tools that show hostnames.
I use Google Workspace or Microsoft 365. Do I need to set this?
No. Their servers send your mail and already have correct reverse DNS. You only manage it for servers you run yourself.