Every .dk domain that delegates its _acme-challenge name to 1e17592b-7e74-49d7-b66d-8bef14a8d620.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.