Every .dk domain that delegates its _acme-challenge name to b48c13be-f5f5-4134-998f-3ebd63c79e9e.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.