Every .dk domain that delegates its _acme-challenge name to ac288521b5a4c52913d4a0d30f9c3d10.dcv.edgeduck.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.