Scylla Manager automatically adds a health check task to all new nodes when the cluster is added to the Scylla Manager and all existing nodes during the upgrade procedure. The health check task ensures that the CQL native port is accessible on all the nodes. For each node, in parallel, Scylla Manager opens a connection to a CQL port and asks for server options. If there is no response or the response takes longer than 250 milliseconds, the node is considered to be DOWN otherwise, the node is considered to be UP. The results are available using the sctool status command.
If you have enabled the Scylla Monitoring stack, the Monitoring stack 2.0 Manager dashboard includes the same cluster status report. In addition, the Prometheus Alert Manager has an alert to report when a Scylla node health check fails, and the node is considered DOWN.