OK that looks good of course. Is there anything in "Failure History"?
I see no "last signal" status so I assume the Signal Count and Signals sections further down in the rule are empty. Can you confirm there are no signals for this rule by searching for *DNS* in the Detections page?
Back in the custom rules list, if you click "Monitoring" can you share the values for this rule? Are there any errors or gaps in the monitoring data or stats for this rule?