Every .dk domain that delegates its _acme-challenge name to dcd0c4d9-1aea-42fa-b9a8-6b82e8e0ad78.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.