Reverse DNS lookup
Find the host name for an IP address, and check that the name points back to it.
Choosing a check opens its page. With the keyboard, use the arrow keys, then press Enter.
What we check
We look up the PTR record for the address, which gives its host name, and then check whether that name points back to the same address. This is called forward-confirmed reverse DNS, and mail servers often rely on it.
Reading the result
- Confirmed: the PTR name points back to this address.
- Not confirmed: the PTR name doesn't point back. Fix it with whoever provides the address, usually your hosting or internet provider.
- No PTR record: common for home and mobile connections. Mail servers need one.
Frequently asked questions
What is reverse DNS?
Normal DNS turns a name into an address. Reverse DNS goes the other way: a PTR record, published by whoever controls the address block, gives a name for an address.
What does "forward-confirmed" mean?
We look up the name from the PTR record and check that it points back to the same address. Mail servers often require this, because anyone who controls an address can publish any name in its PTR record.
Why is there no PTR record?
Many addresses have none. Home and mobile connections often have generic names or none at all. The PTR record is set by the network that owns the address, usually your hosting or internet provider, not in your own domain's DNS.
Why do mail servers care about reverse DNS?
Many receiving mail servers reject or downgrade mail from a server whose address has no PTR record, or whose PTR name doesn't point back to the address.
Can you look up a private address like 192.168.1.1?
No. Private and reserved addresses have no public reverse DNS, so we explain what kind of address it is instead of asking DNS.
Related tools
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IP Lookup
See which network an IP address belongs to, its approximate country, and its reverse DNS name.