According to the Cisco AppDynamics Professional Implementer (CAPI) documents, the REST API for health rule violations allows you to retrieve information about the health rule violations that occurred in a specified time range for a given application1. You can use the REST API for health rule violations for the following valid reasons:

For determining which actions have been executed (B): The REST API response includes the details of the actions that were triggered by the health rule violation, such as email, SMS, HTTP request, or custom action1. You can use this information to verify if the actions were executed successfully, or to troubleshoot any issues with the action execution.

When searching for historical events ©: The REST API allows you to specify a custom time range for retrieving the health rule violations, such as BEFORE_TIME, AFTER_TIME, BETWEEN_TIMES, or BEFORE_NOW1. You can use this feature to search for historical events that occurred in the past, or to analyze the trends and patterns of the health rule violations over time.

The incorrect options are:

For updating an AppDynamics dashboard (A): This is not a valid reason for using the REST API for health rule violations, because the AppDynamics dashboards already display the health rule violations that occurred in the selected time frame, along with the severity, status, affected entities, and actions2. You do not need to use the REST API to update the dashboard, as the dashboard is automatically refreshed with the latest data from the Controller.

For sending emails (D): This is not a valid reason for using the REST API for health rule violations, because the REST API does not send emails directly. The REST API only returns the information about the health rule violations, and the actions that were triggered by them. If you want to send emails based on the health rule violations, you need to configure an email action in the health rule configuration, or use a custom action that invokes an external email service3.

When pushing events to the Event Management System is NOT possible (E): This is not a valid reason for using the REST API for health rule violations, because the REST API does not push events to the Event Management System. The REST API only returns the information about the health rule violations, and the actions that were triggered by them. If you want to push events to the Event Management System, you need to configure an HTTP request action in the health rule configuration, or use a custom action that invokes an external API3.

References:

1: Health Rule Violations API - AppDynamics

2: Health Rule Violations - AppDynamics

3: Actions - AppDynamics