Free Reverse DNS Lookup

What is reverse DNS lookup?

A reverse DNS lookup starts with an IP address and checks for a PTR record that points to a hostname. This is the opposite direction of a typical forward DNS lookup, which starts with a domain or hostname and returns an IPv4 or IPv6 address.

The organization responsible for an IP address controls its reverse DNS entry. A PTR name may describe an Internet provider, mail server, hosting platform or network gateway, but it does not identify the individual person using the connection.

How to perform a reverse DNS lookup

1. Enter a valid public IPv4 or IPv6 address in the tool above.
2. Select Lookup PTR to query its reverse DNS record.
3. Review the returned PTR hostname and reverse DNS name.

You can also select Use my IP to check the public address detected for your current connection. Private and reserved addresses cannot be resolved with public reverse DNS.

How My IP builds the reverse DNS query

The tool validates and converts the address in your browser before contacting the resolver. For IPv4, it reverses the four decimal octets and adds in-addr.arpa. The address 8.8.8.8, for example, becomes the DNS name 8.8.8.8.in-addr.arpa, which is then queried for PTR records.

IPv6 uses a different process. The tool expands the address to all eight groups, pads every group to four hexadecimal characters, reverses the resulting 32 individual hexadecimal digits and adds ip6.arpa. Reversing individual digits rather than complete IPv6 groups is essential for a valid IPv6 PTR query.

Before sending the request, My IP rejects private, loopback, link-local, multicast, documentation and other unsupported ranges. The resulting PTR name is sent to the Google Public DNS JSON API without browser credentials or a referrer. A 12-second timeout prevents the page from remaining indefinitely in a loading state.

Repeatable reverse DNS tests

Enter 8.8.8.8 for a public IPv4 example. The tool should display the generated in-addr.arpa name and any PTR hostname returned by the resolver. Because DNS records can change, treat the live resolver response as authoritative for the time of your check rather than relying on a hostname copied from an older article.

Enter 192.168.1.1 for a private-address test. It should be rejected before a public DNS query is sent. This is the correct behavior: 192.168.1.1 can be reused inside unrelated local networks and its private hostname, if one exists, is available only through the local network's own resolver.

For IPv6, try 2001:4860:4860::8888. The displayed reverse DNS name should end in ip6.arpa. The test confirms that compressed IPv6 notation was expanded and converted; whether a PTR hostname is returned still depends on the network operator publishing one.

Forward DNS vs reverse DNS

What is a PTR record used for?

PTR records are often used in email server checks, network logs and troubleshooting. Mail systems may compare a sending server's PTR hostname with its forward DNS configuration as one of several reputation signals. A PTR record alone does not prove that an address is trustworthy or that a message is legitimate.

IPv4 reverse records are stored beneath in-addr.arpa. IPv6 reverse records use ip6.arpa. This tool builds the correct reverse query automatically after you enter a valid public address.

How to check forward-confirmed reverse DNS

A PTR record points from an IP address to a hostname, but that does not guarantee that the hostname points back to the same address. Forward-confirmed reverse DNS, often abbreviated as FCrDNS, checks both directions.

1. Run the PTR lookup on this page and copy the returned hostname.
2. Open the DNS Lookup tool.
3. Query the hostname's A record for IPv4 or AAAA record for IPv6.
4. Check whether one of the forward results matches the original IP address.

A match provides useful consistency evidence, especially when diagnosing a mail server, but it is not proof that the host is safe or that every message from it is legitimate. Email systems can also evaluate the SMTP hostname, SPF, DKIM, DMARC, reputation and other signals independently of reverse DNS.

Why does an IP address have no reverse DNS?

PTR records are optional. Many residential, mobile, temporary and shared public addresses do not publish one. A missing result does not mean that the IP address is offline, unsafe or unused. It only means that this resolver did not return a public PTR record for the address at the time of the lookup.

How to document and interpret a PTR result

When recording a result for troubleshooting, keep the original IP, IP version, generated reverse name, returned hostname, TTL, resolver and check time. A hostname containing a provider or city code may be an internal naming convention and should not be treated as a precise statement about the user's identity or physical location.

My IP reports the public DNS response without trying to identify the individual behind an address. Learn more about the project's methodology on About My IP, or contact the maintainer if a reproducible conversion or display error occurs.

Reverse DNS questions

To view the approximate location, ISP, organization and ASN of an address, use the IP Address Lookup tool.