In this tutorial, How to Use whois Command on Linux WHOIS (pronounced as the phrase "who is") is a query and response protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP address block or an autonomous system. Quota from Wikipedia Download and install Whois Linux command For Ubuntu, Linux Mint, ElementaryOS and Debian OS: sudo apt-get install whois For CentOS and RHEL: sudo dnf install whois The output terminal as below The syntax whois command whois domain whois public-ip-address whois [options] public-ip-address For example whois command whois huuphan.com whois 172.67.137.70 Getting help whois command $ man whois OR $ whois --help The output terminal as below