You are able to see which repositories your instance is pointing to by taking a look at the "releasever" variable in /and many others/yum.conf – by default, the Amazon Linux AMI has releasever=most up-to-date established. 2. A Virtual non-public server ( VPS ) which has its port 25 open up: https://andreslyitd.blogs-service.com/57958463/the-ultimate-guide-to-red-hat-virtualization-install