CDN zones are part of the Universal Content Delivery Network architecture where the content is located for distribution or from which the content is to be distributed.
Creating or adding a CDN zone requires you to specify the location of your files.
Universal CDN offers three options. Your resources can be located at your own server (Custom location), in the Universal CDN Cloud Storage container (UCDN Storage), or you can set your Amazon S3 storage as origin if your files are located there.