Every .dk domain that delegates its _acme-challenge name to f1228552-51eb-4aa0-8fe5-dd80fc75d15f.13.authorize.certificatemanager.goog. Such CNAMEs hand DNS-01 certificate validation to a shared service, so this list shows who issues TLS certificates through it. Data comes from our own scanners, which re-resolve every .dk domain in the zone roughly once a week.