Every .dk domain that delegates its _acme-challenge name to 4db9c664-9cce-4973-8384-4100801c71c7.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.