Reverse DNS Lookup
Find the hostname behind any IP address. Enter an IPv4 address such as 8.8.8.8 and this tool performs a reverse DNS query to return its PTR record — the name that maps back to that address, resolved live through a public DNS resolver.
What Is a Reverse DNS Lookup?
Normal (forward) DNS translates a hostname into an IP address. Reverse DNS does the opposite: it starts with an IP address and looks up the hostname assigned to it, using a special type of DNS record called a PTR record. To make this work, IPv4 addresses are stored in a dedicated reverse zone (in-addr.arpa) with the octets reversed, so 8.8.8.8 is queried as 8.8.8.8.in-addr.arpa with a PTR query.
Reverse lookups power many everyday things. Email servers use them to verify that a connecting mail server's IP matches its claimed hostname, which helps fight spam. Network administrators use reverse DNS to identify unknown devices on a network, and security analysts trace the owner of an IP. This tool performs that lookup for you in real time — enter any address and get the PTR record instantly.
How to Use This Tool
- Enter an IP address — for example
8.8.8.8,1.1.1.1or2606:4700:4700::1111. - Press Lookup (or hit Enter).
- The tool reverses the address, appends the reverse zone, queries the PTR record and shows the resulting hostname.
- Use the result to confirm an email server's identity, identify a device, or diagnose connectivity issues.
Only the single IP address you enter is sent to the public DNS resolver needed to answer the query — it is never stored or logged by us.
Reverse DNS Lookup — Frequently Asked Questions
What is a PTR record?
A PTR (pointer) record is a DNS record that maps an IP address back to a hostname. It is the reverse of an A or AAAA record. PTR records are published in special reverse zones such as in-addr.arpa for IPv4, and they are what a reverse DNS lookup retrieves.
Why does email end up in spam without reverse DNS?
Many mail servers perform a reverse DNS check on incoming connections. When a server sends mail, the receiving server looks up the PTR record of the sender's IP and compares it with the hostname the sender claims. If the PTR record is missing or mismatched, the message is far more likely to be flagged as spam or rejected outright.
How does a reverse lookup work under the hood?
For an IPv4 address like 8.8.8.8, the octets are reversed and appended to .in-addr.arpa, giving 8.8.8.8.in-addr.arpa. A PTR query is then made against that name. For IPv6, a similar zone (ip6.arpa) is used with the nibbles of the address reversed. The answer contains the hostname assigned to that address.
Does every IP address have a PTR record?
No. Reverse DNS records must be explicitly configured by the organisation that controls the IP address space. Many addresses — especially consumer or dynamically-assigned ones — have no PTR record at all. If none exists, the reverse lookup returns no hostname, which is normal and not necessarily a problem.
Is this reverse DNS tool free and private?
Yes. The tool is completely free and requires no account. It sends only the single IP you enter to the public DNS resolver needed to answer the query, purely to fetch the PTR record. We do not store, log or share the addresses you look up.