How to use Bulk Reverse DNS Lookup
- List the IP addressesPaste IPv4 or IPv6 addresses into One IP per line, with one address on each line.
- Run the lookupPress Run Bulk Reverse DNS Lookup and answer the security check if a challenge appears. Lines that are not valid IPs are skipped.
- Read the hostnamesEach valid address is listed as IP → hostname, or No reverse host when it has no PTR record. Up to 20 addresses are looked up per run.
Common uses
- Put names to the IP addresses in a server log
- Check the reverse DNS of a mail server IP
- Recognise crawler or hosting IPs by their hostnames
Frequently asked questions
How do I use Bulk Reverse DNS Lookup?
1. List the IP addresses: Paste IPv4 or IPv6 addresses into One IP per line, with one address on each line. 2. Run the lookup: Press Run Bulk Reverse DNS Lookup and answer the security check if a challenge appears. Lines that are not valid IPs are skipped. 3. Read the hostnames: Each valid address is listed as IP → hostname, or No reverse host when it has no PTR record. Up to 20 addresses are looked up per run.
Does it show the country or city of an IP?
No. Despite the page address, no geolocation database is used. The tool only performs reverse DNS (PTR) lookups, so you get hostnames, not physical locations.
Where do the hostnames come from?
From the PTR records that the operator of each IP block publishes, looked up through the GigaTools server’s DNS resolver. They can be missing, generic or out of date, and the tool does not check that they resolve back to the same IP.
What happens to invalid lines?
Lines that are not valid IPv4 or IPv6 addresses are skipped and counted, and duplicates are looked up once. Up to 20 addresses are looked up per run, one after another; split longer lists.
Are my IP addresses shared?
They are sent to the GigaTools server, which queries DNS for each one and returns a private, non-cached result. Each run passes a bot check and counts once toward a daily limit per IP address; the tool does not save the list.