The reverse DNS lookup tool resolves an IP address to its PTR hostname record. Enter any IPv4 or IPv6 address to find out what hostname is associated with it — useful for identifying servers, verifying PTR record configuration, and investigating unknown addresses in logs or traffic data.
It is commonly used by system administrators and network engineers to confirm that reverse DNS is correctly configured, or to trace an IP address back to its owner’s infrastructure.
Reverse DNS lookup
Resolve an IP address to its PTR hostname record.
How to use
- Enter an IPv4 or IPv6 address in the input field, such as
8.8.8.8or2001:4860:4860::8888. - Click Look up to query the PTR record for that address.
- Review the result — the resolved hostname or a message indicating no PTR record exists.
- If multiple PTR records are returned, all hostnames are shown.
- Use Copy result to copy the IP and resolved hostname to the clipboard.
What is a PTR record
A PTR record — short for pointer record — is a type of DNS record that maps an IP address back to a hostname. It is the reverse of a standard A or AAAA record, which maps a hostname to an IP address.
PTR records are stored in a special DNS zone. For IPv4, the address is reversed and appended with .in-addr.arpa. For IPv6, the address is expanded to its full nibble form and appended with .ip6.arpa. For example, the PTR lookup for 8.8.8.8 queries 8.8.8.8.in-addr.arpa and returns dns.google.
PTR records are configured by whoever controls the IP address block — typically an ISP or hosting provider. This means not all IP addresses have a PTR record, and the hostname returned does not have to match the forward DNS for that IP.
FAQ
Reverse DNS lookup help
PTR records must be explicitly configured by the owner of the IP address block — usually an ISP or hosting provider. Many IP addresses, particularly dynamic residential IPs or addresses in unmanaged ranges, have no PTR record configured. This is normal and does not indicate a problem with the IP address itself.
Yes. A PTR record is independent of the A or AAAA record for a hostname. The IP 1.2.3.4 might have a PTR record pointing to mail.example.com, but mail.example.com might resolve to a different IP. When forward and reverse DNS match, this is called forward-confirmed reverse DNS (FCrDNS), and it is often used in email server verification.
Many receiving mail servers check that the sending IP has a valid PTR record as part of spam filtering. If no PTR record exists, or if the PTR record does not match the sending hostname, the email may be rejected or marked as spam. A correctly configured PTR record is a standard requirement for email deliverability.
Yes, although this is uncommon. Multiple PTR records on a single IP are technically valid but can cause unexpected behaviour in some email systems and security tools that expect a single authoritative hostname. This tool returns all PTR records if more than one exists.
Yes. Enter a full or compressed IPv6 address such as 2001:4860:4860::8888. The tool automatically builds the correct .ip6.arpa query for the PTR lookup.
Practical examples
Example 1: An unknown IP address appears in your server logs or firewall traffic. Run a reverse DNS lookup to identify the hostname associated with it and determine whether it belongs to a known provider, CDN, or search engine crawler.
Example 2: You set up a new mail server and need to verify that PTR record is correctly configured. Enter the server’s public IP and confirm the returned hostname matches the mail server’s FQDN before testing email delivery.
Example 3: You are investigating an IP address reported in a security alert. A reverse DNS lookup gives you a starting point — the hostname can indicate the owning organisation, hosting provider, or service, which helps with further analysis.
Useful links
- DNS lookup — resolve hostnames to IP addresses and query specific DNS record types.
- My IP and network info — find your public IP address and connection details.
- Port checker — test whether a TCP port is open on a remote host.
Other tools
- DNS lookup — check A, AAAA, MX, TXT, CNAME, NS, and other record types.
- WHOIS lookup — find registration details, owner information, and nameservers for a domain.
- My IP and network info — inspect your public IP, ISP, country, and connection details.
- Port checker — verify whether a specific TCP port is open on a remote host.