If the AD objects belong to one or more Active Directory Protected groups, "Allow Inheritable permissions to propagate to this object and all child objects" check box will be cleared in ADUC (Active Directory Users and Computers) | object Properties | Security tab | Advanced.
Protected Group membership will set the AD object's "adminCount" attribute to "1". This value may be verified using ADSI Edit and connecting to the Default Naming Context.
If "adminCount" is set to "1" the object belongs to the one or more protected groups and permissions inheritance is not set. Permission inheritance, if manually configured, will be reset by default every hour.