Every .dk domain that delegates its _acme-challenge name to c6fb2b9d0fe447f1a72fd41963d17205.cert.prod.ztna.access.sophos.com. 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.