Reverse DNS lookup. Free.
Enter an address and get its PTR record, the network behind it, and what the naming convention gives away about the kind of connection it is.
PTR record for 8.8.8.8
dns.google
Network
Google LLC (AS15169)
Connection type
Data Center
Fraud score
5/100, none risk
Full profile: 8.8.8.8
Pre-filled with a public DNS resolver, which publishes a clean PTR record. Type any address to look up your own.
Behind every check
19.8 million
IP addresses profiled
2.4 million
malicious domains tracked
208,000
disposable email domains
1.9 million
networks scored
Counts read live from the engine, not written into the page. The full dataset is published on GitHub under the MIT license and rebuilt every 30 minutes.
What reverse DNS actually is
Forward DNS turns a name into an address. Reverse DNS does the opposite, turning an address back into a name through a PTR record published in a special zone by whoever controls the address block. The important consequence is that the PTR record is set by the network operator, not by whoever runs the service on that address, which is why you cannot change your own reverse DNS on most connections and why a mismatch between forward and reverse is so common.
Reading a hostname
Reverse DNS names are usually generated from a template, and the template gives away more than operators tend to realise.
pool, dyn, dhcp, cable, dsl
A dynamic consumer connection. The address is handed out to home subscribers and reassigned regularly, which means any history attached to it may belong to someone else entirely.
static, biz, business
A fixed allocation, typically a business line or a server. History attached to it is much more likely to belong to the current holder.
Provider and datacenter names
Cloud and hosting ranges usually name themselves in the PTR. Traffic from them is automation far more often than it is a person browsing.
mail, smtp, mx
A mail server. Receiving mail servers check that the PTR resolves back to the sending name, and a mismatch is one of the most common reasons legitimate mail gets refused.
No record at all
Extremely common and not a fault. Reverse DNS is optional, and huge swathes of cloud address space have none.
Why it matters
Mail delivery
If you run a mail server, a missing or mismatched PTR is one of the first things a receiving server will hold against you. Matching forward and reverse DNS is close to mandatory for reliable delivery.
Reading your own logs
A page of raw addresses tells you nothing. The same page with hostnames resolved usually tells you at a glance whether you are looking at a cloud provider, a search engine crawler, or home connections.
Verifying a crawler is genuine
Anyone can claim to be a search engine in a user agent. The accepted way to verify it is a reverse lookup on the address followed by a forward lookup on the result, checking that it comes back to the same address. A faked user agent cannot survive that.
Classifying traffic
Consumer, business, hosting, or anonymising infrastructure. The PTR is one of the cheapest signals available for telling them apart.
Five PTR lookups, including two with no record.
Live results, fetched as this page loaded. Missing records are shown because they are common and people assume they are errors.
8.8.8.8
5/100 · none
dns.google · datacenter
dns.google. A clean, deliberate PTR record on infrastructure whose operator wants it identifiable.
1.1.1.1
5/100 · none
one.one.one.one · VPN, datacenter
one.one.one.one. Another deliberate name, and a reminder that reverse DNS is chosen by the network, not by you.
185.220.101.34
100/100 · critical
tor-exit-34.for-privacy.net · Tor, VPN, proxy, datacenter
The hostname states the purpose. Naming conventions give away far more than most operators realise.
52.95.110.1
10/100 · none
no PTR record · datacenter
No PTR record at all. Perfectly normal, and very common across cloud address space.
45.148.10.121
100/100 · critical
no PTR record · Tor, datacenter
Also no record. If you are troubleshooting mail delivery, this is the state you need to fix.
Every verdict above was fetched from the engine when this page loaded. Nothing here is a screenshot or a stored example, so if a number looks surprising, that is what our data actually says right now.
Questions people ask
What is a reverse DNS lookup?
It is the process of finding the hostname published for an IP address, the opposite of an ordinary DNS lookup. The answer comes from a PTR record that the operator of the address block controls. Enter any address above and you get its PTR record if one exists, along with the network that owns it.
Why does my IP have no reverse DNS?
Because reverse DNS is optional and a great many addresses simply have none, particularly inside cloud and hosting ranges where addresses are allocated in bulk. It is not an error and for most purposes it does not matter. The exception is running a mail server, where a missing PTR will get your mail refused.
How do I change my reverse DNS?
Only the operator of the address block can, which is your hosting or internet provider rather than you. On a server you have usually rented, the provider's control panel has a field for it. On a home connection you almost certainly cannot change it at all, since the address is not yours.
What is the difference between reverse DNS and rDNS?
Nothing. rDNS is just the abbreviation, and PTR record is the name of the specific DNS record type that holds the answer. All three refer to the same thing.
Is reverse DNS reliable for identifying who owns an address?
It is a strong hint and not proof. The PTR is set by whoever controls the address block and can say anything they like, so it should be corroborated with WHOIS registration data and the autonomous system the address belongs to, both of which we show alongside it. For verifying a crawler specifically, the reliable method is a reverse lookup followed by a forward lookup on the result to confirm it points back to the same address.
Other free tools
Free IP lookup
Owner, network, autonomous system, reverse DNS, and approximate location for any address.
ASN lookup
Find the organisation behind any network by AS number or IP, and how abusive its observed traffic is.
IP reputation
A 0 to 100 fraud score for any IP address, with every signal that produced it shown in the open.
Do it in code.
The same answer from a free API endpoint, or download the whole database and never call an API at all. No card, no quota, no expiry.