It can be anything! An apex, subdomain, or even a URL.
s3.dal.us.private.cloud-object-storage.test.appdomain.clouddal.us.private.cloud-object-storage.test.appdomain.cloudus.private.cloud-object-storage.test.appdomain.cloudprivate.cloud-object-storage.test.appdomain.cloudcloud-object-storage.test.appdomain.cloudtest.appdomain.cloudappdomain.cloudcloud