Every .dk domain that delegates its _acme-challenge name to 7c6283fe-3cb5-4ecd-8259-a39a0871a5d8.auth.zigza.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.