Every .dk domain that delegates its _acme-challenge name to a37fe172-c03e-4ed6-b1d9-cb6d12e8fea7.13.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.