According to the EC2 documentation, the internal NTP is preconfigured on Amazon Linux 2, Amazon Linux AMI and Amazon Windows AMI. For the other distros (and all old instances) it is up to the server operator to set up time sync or it will use distro defaults. So the rollout is still far from finished. And even if you follow the official manual, that just ensures that you add the local ntp service to the config, next to the other servers…