To install the whois command on RHEL 8 / CentOS 8, you can use the package manager dnf:
sudo dnf install whois
This will install the whois package, which provides the whois command-line tool for querying domain name registration information. Once installed, you can use the whois command to look up information about a domain or IP address.
For example, to look up information about example.com, you would run:
whois example.com
After installing it you can also use whois command to lookup IP addresses or ASNs to get more information about the entity that owns them.