Free Reverse DNS Lookup

Reverse DNS maps an IP address back to a hostname using PTR records in the in-addr.arpa zone.

Email deliverability verification, network diagnostics, and identifying server owners.

Yes, completely free.

Absolutely. The Reverse DNS Lookup processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the Reverse DNS Lookup is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the Reverse DNS Lookup in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The Reverse DNS Lookup works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

Forward DNS resolves a name to an IP address: you ask for example.com and get back something like 93.184.216.34, using A records for IPv4 or AAAA records for IPv6. Reverse DNS does the opposite, mapping an IP back to a hostname using a PTR record stored in a special zone. For IPv4 the address is reversed octet by octet under in-addr.arpa, so 1.1.1.1 is queried as 1.1.1.1.in-addr.arpa; IPv6 reverses each hex digit under ip6.arpa. The two directions are configured separately and do not have to agree, which is why an IP can resolve to a hostname that does not point back to that same IP. This tool builds the reversed arpa query name for you automatically, so paste an IP and it returns the PTR hostname without manual assembly.

Reverse DNS only works when whoever administers the IP block has published a PTR record for that address. Many residential, mobile, and cloud IPs simply have none, or return a generic provider-assigned name rather than a branded hostname, because the network owner never configured one. Unlike forward DNS, which a website operator controls directly, reverse DNS is set by the party that controls the IP range, so you cannot add a PTR record for an address you do not own. When no record exists, the resolver returns an NXDOMAIN response, and this tool reports that plainly instead of guessing a name. Missing reverse DNS is common and usually harmless, though it can hurt email deliverability for a sending mail server. Enter any IP above to see whether a PTR record has actually been published for it.

Large mail providers like Gmail and Outlook check that a sending server's IP has a valid PTR record before accepting its mail, and they prefer reverse DNS that matches the server's forward DNS — a setup called Forward-Confirmed reverse DNS, or FCrDNS. The logic is simple: a legitimate, well-configured mail server almost always has clean reverse DNS, while spam sources frequently do not. If your sending IP has no PTR record, or one that resolves to a generic provider hostname instead of your mail domain, your messages are more likely to land in spam or be rejected outright. Checking the PTR record is one of the first diagnostics when mail mysteriously stops being delivered. Paste your sending IP above to confirm it resolves to a sensible, matching hostname before you troubleshoot anything else.

No. A PTR record shows only what the IP block's administrator chose to publish, not who legally controls the address, so treat the hostname as a strong hint rather than proof of identity. Whoever manages the IP range sets the reverse DNS, and they can point it at any name they like, which means it is informative but not authoritative. It is excellent for recognizing a CDN, a known crawler, or a hosting provider at a glance in server logs, and as a fast first clue during a security investigation. For genuine ownership of an address you should pair this lookup with a WHOIS query on the IP's network range, which returns the registered organization. Enter an IP above to read its published PTR hostnames, then verify anything important against WHOIS.

IPv6 reverse DNS follows the same idea as IPv4 but uses a different zone and a finer breakdown. Instead of reversing four octets under in-addr.arpa, every single hexadecimal digit of the fully expanded 128-bit address is reversed and placed under ip6.arpa, producing a long query name with 32 nibble labels. Because IPv6 addresses are often written in shorthand with a double colon standing in for runs of zeros, the address has to be expanded to its full form first before the digits can be reversed. This tool handles that expansion automatically: enter a compressed address like 2606:4700:4700::1111 and it fills in the omitted zero groups, builds the matching ip6.arpa PTR name, and resolves it. Try one of the IPv4 example addresses or paste a full IPv6 address above to see its hostname.