Azure AD Connect is a very important service, it is the connection between your Active Directory on-premises and you Azure AD in the cloud. Normally, you do not have a test possibility and all changes are on live system.
The purpose of this topic is to describe supported and unsupported changes to Azure AD Connect sync. The configuration created by Azure AD Connect works “as is” for most environments that synchronize on-premises Active Directory with Azure AD. However, in some cases, it is necessary to apply some changes to a configuration to satisfy a particular need or requirement.
It describes the following topics related to change son Azure AD connect configuration:
- Changes to service account
- Changes to scheduler
- Changes to synchronization rules
Read the whole article on Microsoft docs here: https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnectsync-best-practices-changing-default-configuration