Reverse DNS Lookup

Resolve PTR records and verify forward-confirmed reverse DNS
This free online reverse dns lookup runs in your browser and is part of our Developer Tools collection.

Reverse DNS Lookup

Resolve an IP address to its PTR hostname and perform an optional forward-confirmation check.

What this helps with

  • Validate PTR records for mail and infrastructure hosts
  • Triage suspicious traffic sources by hostname patterns
  • Learn forward-confirmed reverse DNS behavior
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Instant In-Browser Execution Runs locally in JavaScript without wait times or server delays.
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100% Privacy & Security Your inputs and files are never stored or logged on remote servers.
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Cross-Device Responsive Fully optimized for mobile smartphones, tablets, and desktop displays.
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100% Free Forever No subscription fees, no signups, and no software installations.

How to Use the Online Reverse DNS Lookup

1 Enter IP Address

Input any public IPv4 or IPv6 address (e.g. `8.8.8.8` or `1.1.1.1`).

2 Query PTR Record

Click "Lookup Reverse DNS" to query the `in-addr.arpa` or `ip6.arpa` DNS pointer record.

3 Inspect Resolved Hostname

Review the fully qualified domain name (FQDN) assigned to the IP address by the network operator.

4 Verify Forward-Confirmed rDNS (FCrDNS)

The tool checks if the resolved hostname points back to the original IP address to verify reverse DNS integrity.

Frequently Asked Questions

Common questions about using this free online reverse dns lookup.

What is Reverse DNS (rDNS) and PTR records? ▾
Standard DNS resolves hostnames to IP addresses. Reverse DNS (rDNS) performs the opposite operation, resolving an IP address back to its associated domain name using a special Pointer (PTR) record.
Why is reverse DNS mandatory for sending email servers (SMTP)? ▾
Major email providers (Gmail, Outlook, Yahoo) automatically reject or spam-flag emails sent from servers without valid rDNS and Forward-Confirmed rDNS (FCrDNS) as an anti-spam safeguard.
Who is responsible for setting up reverse DNS for an IP address? ▾
The organization that owns the IP allocation (your hosting provider, cloud vendor, or ISP) controls reverse DNS delegation in regional registries (ARIN, RIPE, APNIC).
Can private IP addresses (like 192.168.1.1) be looked up in public rDNS? ▾
No. RFC 1918 private IPs are non-routable on the public internet and can only be resolved by internal enterprise DNS servers.

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