Enter an IPv4 or IPv6 address to find its PTR record, the hostname the network owner assigned to it. Paste a whole list or a log file in bulk mode, and check forward-confirmed reverse DNS, which mail servers use to judge senders.
Last updated:
IP address
PTR hostname
Forward-confirmed
TTL
Advertisement
Advertisement
How to use the Reverse DNS Lookup
Enter an IP address such as 8.8.8.8 or 2606:4700:4700::1111 and click Find hostname.
Switch to Bulk to look up many addresses: paste one per line, a CIDR range, or any text that contains IPs.
Keep Forward-confirm on to check that each PTR hostname resolves back to the same IP.
Read the results: hostname, FCrDNS status, TTL and the reverse name that was queried.
Export the table as CSV or copy it for a report or spreadsheet.
How reverse DNS names are built
PTR records live in two special DNS zones. The tool converts your address into the right name automatically, but this is what it queries:
IPv4 octets are reversed because DNS names are read from the most specific label on the left to the least specific on the right, while IP addresses go the other way. IPv6 addresses are expanded to all 32 hex digits first, then reversed digit by digit.
Reading the results
Result
Meaning
Hostname shown
The IP has a PTR record. Generic names such as 203-0-113-7.dynamic.isp.net usually mean a home or dynamic connection.
No PTR record (NXDOMAIN)
The owner of the IP block has not set a reverse name for this address.
Server failure
The reverse zone is delegated to name servers that do not answer correctly.
✓ Confirmed
The hostname resolves back to the same IP (FCrDNS passes).
✗ Points elsewhere
The hostname exists but resolves to different IPs. Mail servers may treat this as suspicious.
Private / Documentation tags
Reserved ranges (RFC 1918, RFC 6598, RFC 5737, RFC 4193) that have no public reverse DNS.
Why reverse DNS matters for email
Most receiving mail servers look up the PTR record of the connecting IP. A missing PTR, a generic dynamic-looking name or a failed forward confirmation are classic spam signals, and some providers reject such connections outright. If you run a mail server, set its PTR to the hostname it announces in HELO/EHLO, make sure that hostname has an A or AAAA record pointing back to the IP, and pair it with valid SPF and DMARC records (check them with the SPF Record Checker and DMARC Checker). To see where an address is located, use the IP Geolocation Lookup.
Frequently asked questions
What is a reverse DNS lookup?
A normal DNS lookup turns a name into an IP address. A reverse lookup does the opposite: it asks for the PTR record of an IP address, stored under a special name such as 8.8.8.8.in-addr.arpa, and returns the hostname the owner of that address block configured.
How is the reverse name built?
For IPv4, the four octets are written in reverse order followed by in-addr.arpa, so 192.0.2.10 becomes 10.2.0.192.in-addr.arpa. For IPv6, the full 32 hex digits are reversed one nibble at a time, separated by dots and followed by ip6.arpa.
Why does an IP have no PTR record?
PTR records are managed by whoever controls the IP block, usually the hosting provider or ISP, not by the owner of a domain. Many home connections, cloud instances and private addresses (such as 192.168.x.x) simply have none, or have a generic one set by the provider.
What is forward-confirmed reverse DNS (FCrDNS)?
FCrDNS means the PTR hostname of an IP also resolves back to that same IP with an A or AAAA lookup. Mail servers commonly require it for senders, and it proves the PTR was set by someone who also controls the hostname's forward zone.
How do I change the PTR record of my server?
Ask the provider that assigned the IP address. Most VPS and cloud dashboards have a reverse DNS or PTR field per IP. Set it to a hostname that has an A or AAAA record pointing back to the IP so FCrDNS passes.
Can a single IP have several PTR records?
Yes, it is allowed, and the tool lists all of them. In practice one PTR per address is recommended, because many systems only use the first answer.
Is this lookup private?
Queries go directly from your browser to Cloudflare's or Google's public DNS-over-HTTPS service. FreeToolCabin runs no server for this tool and does not see or store the addresses you look up.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.