The nameserver pdns71.ultradns.com appears in the delegation of 4 .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, 0 (0.0%) validate as secure — below the zone-wide average of 62.7%, while 3 (75.0%) are unsigned, with none failing validation outright — a further 1 come back indeterminate.

One thing worth flagging: 1 of these domain (25.0%) 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.