Every .dk domain that delegates its _acme-challenge name to 5efb439c-5866-43a5-a2b8-e29d59573718.c-29b0.tx.auth.certifytheweb.com. 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.