Every public IP address used on the Internet is registered to an owner. The owner may be an individual or a representative of a larger organization (such as an Internet service provider).

WHOIS

The WHOIS database tracks the owners of public IP addresses on the Internet. For a given IP address, you can query the database for the following information:

Owner name and contact telephone number
Dates of registration
List of other IP addresses in that range with the same owner
List of DNS servers associated with that IP range

Various WHOIS lookup services are available online.

Private and Other Reserved IP Addresses

Some IP address ranges are reserved for use on private networks or for Internet research. Attempting to look up these addresses in WHOIS will return an owner such as Internet Assigned Numbers Authority (IANA). However, these same addresses are actually employed on many different home and business networks worldwide.

To find the owner of a private IP address within an organization, contact a system administrator for their network.