Due to an unfortunate bug in a recent probe firmware (version 4760), TCP based DNS measurements are not providing correct results. This affects all ongoing and one-off measurements.
The issue also affected DNSMON measurements between 14-23 March. On 23 March we deployed a corrected firmware on RIPE Atlas anchors (version 4770), and in the near future we'll deploy it on regular probes as well.
Our excuses for the inconvenience caused!