Reverse DNS Lookup
Find the host name behind any IPv4 or IPv6 address, up to 50 at a time, and check that the name points back to the same IP. That forward-confirmed reverse DNS is what receiving mail servers look for.
Reverse DNS Lookup
How this lookup works. When you press Reverse lookup, your browser sends the question over encrypted DNS-over-HTTPS to Cloudflare's public resolver (1.1.1.1), or to Google Public DNS (8.8.8.8) if you choose it below. The request goes straight from your device to them. It doesn't pass through ToolFeather: we have no server in the path, so we never see or store the names you look up. Requests are sent without cookies or a referrer. Each resolver has its own privacy policy: Cloudflare · Google.
Results appear here.
Queries your browser sent (0)
These are the exact requests, each one a link. Open one to see the raw JSON answer from the resolver.
Live lookup: your browser asks Cloudflare or Google DNS directly. Nothing passes through ToolFeather.
Scratchpad auto-saved
How it works — in four simple steps
No signup and nothing to install — it all runs in your browser.
Paste IP addresses
One per line, IPv4 or IPv6.
Reverse lookup
PTR and forward lookups run in parallel.
Check the status
Forward-confirmed, mismatched, or no PTR.
Fix at your provider
Set the PTR in your hosting or cloud console.
Mail servers need a PTR name that resolves back to the same IP. Set it in your hosting provider's panel.
Features
IPv4 and IPv6
Builds the in-addr.arpa or ip6.arpa name for you, nibble by nibble.
Bulk lookups
Up to 50 addresses at once. Paste log lines and the IPs are picked out.
FCrDNS check
Confirms each PTR name resolves back to the same IP, as mail servers require.
Special ranges
Labels private, loopback, CGNAT and documentation addresses.
Plain guidance
Explains who controls reverse DNS for an address and where to change it.
About the Reverse DNS Lookup
Normal DNS turns names into addresses. Reverse DNS turns an address back into a name, using PTR records in special zones. For IPv4 the address is reversed under in-addr.arpa, so 8.8.4.4 becomes 4.4.8.8.in-addr.arpa. For IPv6 every hex digit is reversed under ip6.arpa, which makes a 72-character name. The tool builds these names for you and shows them.
A PTR record alone proves little, because whoever controls an IP block can make it say anything. Mail servers check forward-confirmed reverse DNS (FCrDNS): the PTR name's own A or AAAA record must include the original IP. Gmail requires sending IPs to have valid forward and reverse DNS, and many receivers spam-folder or reject mail from IPs without it. The tool runs that forward check on every PTR name it finds.
Reverse DNS is set by whoever owns the IP range, usually your hosting or cloud provider, not in your domain's DNS. In AWS, Google Cloud, Azure, DigitalOcean, Hetzner and most VPS panels look for "reverse DNS" or "PTR". Private addresses (10.x, 192.168.x, fc00::/7) have no public reverse DNS. Only your own network's DNS server can answer for them.