You can quickly run transaction SU01 and see if the “Systems” tab is available. If it is then CUA has been configured. Well there is another way to see whether CUA is used. Run transaction code SCUA to see if there are any distribution models defined. Run transaction code SCUL to see to view logs that are generated by CUA & if you have logged into a child system, then goto transaction code SU01 and see, there will be no CREATE activity.