Do you often get confused between alert generated and Nutanix Cluster Check (NCC) failure?

Here are some points to understand them both:

Alert: Mechanism to report underlying issues in the system. 
NCC: Tool to check the cluster health and report alert if required. (If there is a NCC failure then it does not always generates an alert.)

Three important sections of the above diagram:

1. Notifications received - Cluster Health service.
2. Configuration stored - IDF database.
3. Alert reported - Alert Manager.

Configuration and Alert Reporting:

The alert reporting is based on the above configuration.

We can also fetch the above information via "ncli alerts get-alert-config" and update using "ncli alerts update-alert-config"

Tools:

For checking the alerts received to nos-alert: Zygrade
For checking the alert: Insights
 

Logs/Command: 

Alert Manager leader: alert_tool 
To check if the alert notification is send to email recipients: "alert_manager.INFO" log file in the alert manager leader. 
To check about the alert generating notification/plugin: "health_server.log" log in the node generating the alert.

KB:

KB 1959 Which Alerts Automatically Generate a Support Case with Nutanix Support? 

KB 2595 Nutanix Support Services: Pulse and Alerts