How to disable automatic updates on Fedora 25?

dnf is a background service that updates the repository metadata automatically. dnf makecache is scheduled to run after every reboot

To disable dnf-makecache.service:

systemctl disable dnf-makecache.service 

Also disable the dnf-makecache.timer or the service will be restarted:

systemctl disable dnf-makecache.timer

Regards