Every .dk domain that delegates its _acme-challenge name to 860c0a7c-130e-49dd-9b54-79dca1e44c8d.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.