Every .dk domain that delegates its _acme-challenge name to 2ea40289-eae7-4765-a28d-4ad7bf97568d.acme-auth.itcn.dk. 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.