CentOS

-CentOS Project
--https://www.centos.org/

-CentOS-announce Info Page
--https://lists.centos.org/mailman/listinfo/centos-announce

-Red Hat Product Advisories - Red Hat Customer Portal
--https://access.redhat.com/security/security-updates/

-DNF Command Reference — dnf latest documentation
--https://dnf.readthedocs.io/en/latest/command_ref.html

-CentOS Mirror
--http://mirror.centos.org/
-->This directory tree contains current CentOS Linux and Stream releases.

-CentOS Vault
--http://vault.centos.org/

-Debuginfo Packages
--http://debuginfo.centos.org/

-Is it possible to limit yum so that it lists or installs only security updates? - Red Hat Customer Portal
--https://access.redhat.com/solutions/10021

-CentOS Linux 8
--http://www.nilab.info/wiki/CentOS_Linux_8.html

-CentOS Stream 8
--http://www.nilab.info/wiki/CentOS_Stream_8.html