Every .dk domain that delegates its _acme-challenge name to 51a0d170-ecef-40ba-8480-f96363e52c78.auth.acme-dns.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.