Every .dk domain that delegates its _acme-challenge name to 8f64548f-ebe2-4d61-b3ac-db1d15ba0f9e.acme-auth.itcn.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.