Every .dk domain that delegates its _acme-challenge name to 36ca28c5-50df-440f-8b43-9bb0b49e1124.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.