Every .dk domain that delegates its _acme-challenge name to f33708d9-156a-4ab3-8a27-37221d2d335c.16.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.