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Reverse DNS (PTR) Lookup

Look up the PTR (reverse DNS) records for an IPv4 or IPv6 address and see the hostname(s) the address resolves back to.

How to use this tool

  1. 1

    Type or paste an IP address into the input box, for example 8.8.8.8 or an IPv6 address like 2001:4860:4860::8888.

  2. 2

    Click Lookup to send the address to our server, which runs a reverse DNS (PTR) query against the public DNS system.

  3. 3

    Read the returned hostnames in the results list, or the 'No PTR record found' notice if the address has no PTR record or the lookup fails.

  4. 4

    Try another address to compare results, for example a mail server IP versus a residential or cloud IP.

What is reverse DNS and what does a PTR lookup return?

Forward DNS maps a hostname to an IP address (example.com to 93.184.216.34). Reverse DNS does the opposite: given an IP, it asks 'which hostname is registered for this address?' The answer lives in a PTR record stored under the special in-addr.arpa zone for IPv4 and ip6.arpa for IPv6. For 8.8.8.8 the resolver actually queries 8.8.8.8.in-addr.arpa and reads back the PTR value, here dns.google. This tool sends your IP to our server, which calls Node.js dns.reverse() and returns every PTR hostname the address resolves to as a plain list. An address can legitimately have zero, one, or multiple PTR records. Control of a reverse zone is usually delegated to the network operator who owns the IP block, so for cloud or hosting IPs you often set PTR records through your provider's control panel rather than your own DNS. Note this is a one-way lookup: it does not perform forward-confirmed reverse DNS (FCrDNS), meaning it does not re-resolve the returned hostname back to the IP to confirm the pair matches. It also does not validate WHOIS ownership or geolocation.

Common use cases

  • Confirm a sending mail server's IP has a valid PTR record before going live, since Gmail and Microsoft 365 often reject or junk mail from IPs with no reverse DNS.

  • Read web server or firewall access logs and turn raw IP addresses into hostnames to spot which networks or providers are connecting.

  • Verify that a cloud or VPS provider correctly applied the custom PTR record you requested for an outbound IP.

  • Investigate a suspicious IP during incident response to see whether it points back to a known ISP, hosting company, or CDN.

  • Sanity-check a newly delegated IP block by confirming PTR records resolve as expected after a network migration.

  • Troubleshoot SSH or service connections where the daemon does a reverse lookup on the client IP and a missing PTR causes slow or failed logins.

Frequently asked questions

Does this tool run in my browser or on your server?▼
On the server. The IP you enter is sent to our backend, which performs the DNS query and returns the result. The lookup is not done in your browser, so do not treat the IP you submit as private to your device.
Why does Gmail care about PTR records?▼
A valid PTR record signals that whoever controls the sending IP also controls its reverse DNS zone, which is a basic sign of a legitimate operator rather than a hijacked or botnet host. Gmail and Microsoft commonly reject or junk mail from IPs that have no reverse DNS at all.
Why do I get 'No PTR record found'?▼
Either the IP genuinely has no PTR record, the reverse zone is not delegated, or the underlying DNS query returned an error (for example an invalid address or a resolver timeout). Many residential and freshly provisioned cloud IPs simply have no PTR set until the network operator adds one.
Does it support IPv6?▼
Yes. Node's dns.reverse() handles both IPv4 (in-addr.arpa) and IPv6 (ip6.arpa) addresses, so you can paste an address like 2001:4860:4860::8888 and get its PTR hostname.
Can one IP return more than one hostname?▼
Yes. An address may have multiple PTR records, and the tool lists all of them. Multiple PTRs are allowed by DNS but are uncommon and some mail systems only honor the first one.
Does it confirm the hostname maps back to the IP (FCrDNS)?▼
No. This is a plain reverse lookup. It does not re-resolve the returned hostname forward to check it points back to the same IP, which is what forward-confirmed reverse DNS (FCrDNS) checks. Use a dedicated FCrDNS or mail-deliverability tool if you need that verification.
How current are the results?▼
The lookup is live at the moment you click Lookup, but DNS caching means a recently changed PTR record may take time to propagate. If you just updated a PTR with your provider, allow for the record's TTL before expecting the new value everywhere.

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