By Debmedia Technologies LLP · Kolkata, India · Updated
What Is an IP to Hostname Lookup?
An IP to hostname lookup finds the domain name that an IP address points back to. It works through reverse DNS, which stores a PTR record for the address. Instead of asking “what address does this name have?”, it asks the reverse: “what name does this address have?”
The result is useful for reading server logs, identifying a connection, checking an email server and spotting suspicious traffic. A hostname such as mail.example.com tells you much more than a bare number.
How to Use This Tool
- Enter an IPv4 or IPv6 address, for example 8.8.8.8.
- Press Find hostname.
- Read the hostnames found and the forward check next to each one.
- Review the reverse DNS name that was queried at the bottom of the result.
How Reverse DNS Works
For IPv4 the octets are reversed and in-addr.arpa is added, so 8.8.8.8 becomes 8.8.8.8.in-addr.arpa. For IPv6 each of the 32 hex digits becomes a label in reverse order under ip6.arpa. The tool builds the right name for you and then asks for the PTR record, which is defined in RFC 1035, which defines PTR records.
| Result | What it means |
|---|---|
| Matches | The hostname resolves back to the same IP address. This is called forward-confirmed reverse DNS. |
| Does not match | The name exists, but it points to a different address. Treat it with care. |
| No PTR record | The owner never set up reverse DNS for this address. |
Common Uses
- Email delivery. Many mail servers reject mail from addresses without matching reverse DNS. Check your sending address here.
- Log analysis. Turn the addresses in access logs into names to see whether visitors are search engines, cloud servers or home users.
- Security checks. A name that does not match its address is a reason to look closer.
- Network troubleshooting. Hostnames of routers often reveal the provider and the location.
How to Set or Fix a PTR Record
Only the owner of the address block can change its PTR record. For a server, open your hosting provider’s control panel and look for a reverse DNS or PTR setting. For a home connection, ask your internet provider. Make sure the hostname you choose has an A or AAAA record pointing back to the same address.
To see who owns the block, try the WHOIS owner lookup. To go the other way and list the addresses of a name, use the domain address finder.
Frequently Asked Questions
Disclaimer: results come from live requests and can change as records and servers change. We cannot guarantee that every answer matches what every visitor sees.