Every .dk domain that delegates its _acme-challenge name to 266fdb15-70b6-46f5-9f8b-921a315afa7d.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.