Every .dk domain that delegates its _acme-challenge name to de9f6ad0-bfca-4eaf-adab-f4645cd9c7b0.auth.acme-dns.io. 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.