• Linux Security: https://linuxsecurity.com/
• The official VirtualBox website: https://www.virtualbox.org/
• The Ubuntu "Alternate Installer" download page: https://ubuntu.com/download/alternative-downloads#alternate-ubuntu-server-installer
• The official CentOS page: https://www.centos.org/
• RHEL documentation (this also works for CentOS): https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/
• How to Set Up Automatic Updates on Ubuntu Server 18.04: https://libre-software.net/ubuntu-automatic-updates/
• Enabling Automatic Updates in RHEL 7 and CentOS 7: https://linuxaria.com/howto/enabling-automatic-updates-in-centos-7-and-rhel-7
• Managing and Monitoring Security Updates for RHEL 8: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_and_monitoring_security_updates/index