Every .dk domain that delegates its _acme-challenge name to 45fe0ed2-aa09-48d4-8d1f-bff55e948684.auth.acme-challenge.dk. 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.