WHOIS for IP, IPv6 and Websites - Information Gathering
Here you can find out whois information about IP and site addresses (domains). Whois information very often contains information about the range to which the IP belongs, about the company to which the IP belongs, information for contacting the contact person (phone numbers, e-mail addresses, postal addresses). Information about domain names (about sites) includes name, phone numbers, postal and email addresses of the site owner, name servers. Sometimes the information is hidden.
This online service whois supports IPv6 as well.