The nameserver ns2.concrete5danmark.dk appears in the delegation of 49 .dk domains in our dataset — <0.01% of every scanned .dk domain. The full list is below — here is how those domains look under the hood.

On the DNSSEC side, 2 (4.1%) validate as secure — below the zone-wide average of 62.7%, while 44 (89.8%) are unsigned, with none failing validation outright — a further 3 come back indeterminate.

One thing worth flagging: 3 of these domains (6.1%) look like lame delegations — the .dk registry still points them here, but this nameserver doesn't answer authoritatively for the zone, which usually means the hosting was cancelled and the delegation was left dangling.