I've been testing DNS Cluster.
I have one working DNSONLY server in the cluster, no problems.
I blocked IP address of the web server in the DNSONLY server, and changed " Failure threshold for cluster members: 2".
I made some DNS changes in the webserver, and it took long time (over a minute) to finish it.
I went to WHM->Clusters->DNS Cluster, and the nameserver was showing "Disabled due to connection failures.".
In Global DNS Cluster Options I had selected " Receive a notification when WHM disables an unresponsive cluster member ".
I never got any notice.
I have one working DNSONLY server in the cluster, no problems.
I blocked IP address of the web server in the DNSONLY server, and changed " Failure threshold for cluster members: 2".
I made some DNS changes in the webserver, and it took long time (over a minute) to finish it.
I went to WHM->Clusters->DNS Cluster, and the nameserver was showing "Disabled due to connection failures.".
In Global DNS Cluster Options I had selected " Receive a notification when WHM disables an unresponsive cluster member ".
I never got any notice.