Custom Dimension values can be viewed for dates before the custom dimension was created by using them as Primary Dimension in Custom Reports. This will give you all the Custom Dimension and Custom Metric values you created. This data won’t be available if you use Custom Dimensions as Secondary Dimension in Standard report.
This question is a part of the Google Analytics Individual Qualification. You can get all the answers with detailed explanation for this exam in our Google Analytics Individual Qualification Exam Answers page.