Every .dk domain that delegates its _acme-challenge name to 31e98f9d-d710-41be-9289-c7f35ee7be32.9.authorize.certificatemanager.goog. 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.