Sun Cluster HA for DNS Fault Monitor

The probe uses the nslookup command to query the health of DNS. Before the probe actually queries the DNS server, a check is made to confirm that network resources are configured in the same resource group as the DNS data service. If no network resources are configured, an error message is logged and the probe exits with failure. The probe executes the following steps.

1. Run the nslookup command by using the time-out value specified by the resource property Probe_timeout.

   The result of this nslookup command can be either failure or success. If the nslookup query was successfully replied to by DNS, the probe returns to its infinite loop, waiting for the next probe time.

   If the nslookup fails, the probe considers this scenario a failure of the DNS data service and records the failure in its history. The DNS probe considers every failure a total failure

2. Based on the success/failure history, a failure can cause a local restart or a data service failover. This action is further described in "Health Checks of the Data Service".