Every .dk domain that delegates its _acme-challenge name to 1c3c12ec-b820-477c-a2fa-3b051df0739d.15.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.