Every .dk domain that delegates its _acme-challenge name to 856b448f-a3b8-4b62-817a-e1d15063308b.auth.siteworks.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.