Every .dk domain that delegates its _acme-challenge name to ca976948-8c0f-4543-8794-9a66ea3aa53d.19.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.