As per 16:20CET update at https://transnoc.nl/, TransIP have situation under control and we can confirm that DNS requests are not failing now.
Posted Mar 22, 2021 - 17:00 CET
We are continuing to work on a fix for this issue.
Posted Mar 22, 2021 - 15:48 CET
Currently users may experience DNS resolving issues or slow connections due to DDoS attack on our domain registrar TransIP name servers. This situation is beyond our control, and is being tracked at https://transnoc.nl/.
Posted Mar 22, 2021 - 15:45 CET
This incident affected: Acceptance Test Environment (Portal, API v2, Connectors), Tradecloud One Portal, and Connectors (API v2 Connector, Isah SCI Connector).