Explanation
To confirm that the agent is communicating properly to the controller, you can use the following methods:
Check if data is being written to the agent log in /logs. This indicates that the agent is able to send metrics and events to the controller. You can also look for any errors or warnings in the log file that might indicate a connection issue1 Select Application > Tiers and Nodes > Look for the Node. This shows you the list of nodes that are registered with the controller and their status. You can see if the node is up or down, the agent version, the last reported time, and the machine name2 References: 1: Troubleshoot Agent Connectivity 2

Explanation
According to the Time Range Comparisons document1, you can use the Compare Time Range feature in Dash Studio to compare two time periods on a widget. However, this feature also means that the widget may not use the global time range set for the entire dashboard by default. Instead, the widget may use its own time range (denoted as T1) and a second time range (denoted as T2) for comparison. Therefore, if the customer changes the time range using the time picker, the data on the widget may not change accordingly, unless they also update the widget's time range settings. Tofix this problem, the customer can either disable the Compare Time Range feature or adjust the widget's time range to match the global time range. References:
Time Range Comparisons

Explanation
An exception in AppDynamics is a code-level event that indicates a problem or abnormality in the execution of a business transaction. AppDynamics captures and presents information on exceptions in the monitored environment, and allows you to configure the rules and criteria for detecting and reporting exceptions.
According to the Errors and Exceptions - AppDynamics, the following two types of events would be marked as an exception in AppDynamics:
A custom-configured error method and error message: This is a type of event that you can define as an exception based on a specific method and message that indicate an error condition in your application code. You can configure the error detection rules to mark a business transaction as an error and capture the exception information when such a method and message are encountered. For example, you can configure a rule to mark a business transaction as an error and capture the exception when the method com.example.MyClass.myMethod returns the message Invalid input.
Any message that is logged with a severity of Error or Fatal: This is a type of event that AppDynamics automatically detects as an exception based on the log messages that are generated by your application code. AppDynamics scans the log messages for the keywords Error or Fatal, and marks the business transaction as an error and captures the exception information when such a message is found. For example, AppDynamics will mark a business transaction as an error and capture the exception when the log message contains Error: Null pointer exception.
Therefore, B (a custom-configured error method and error message) and C (any message that is logged with a severity of Error or Fatal) are two types of events that would be marked as an exception in AppDynamics.
References:
Cisco AppDynamics Associate Administrator Certification
Errors and Exceptions - AppDynamics
Error Detection - AppDynamics

Explanation
Health Rules are the rules that define the normal or expected behavior of your application, such as the response time, error rate, or CPU utilization of a business transaction, tier, node, or backend. You can create health rules to monitor the performance and availability of your application and its components. When a health rule is violated, it changes the status of the corresponding key performance indicator (KPI) from normal to warning or critical, depending on the severity of the violation. The status change is also represented as an event in the AppDynamics Controller UI, which can trigger alerts, policies, and actions. You can view the health rule events in the Events tab of the application dashboard, or in the Health tab of the entity dashboard.
https://developer.cisco.com/docs/appdynamics/health-rules/
https://university.appdynamics.com/certifications/associate-administrator

Explanation
The custom dashboard feature in AppDynamics allows you to display a specific set of metrics and data points on one screen. You can use custom dashboards to present selected metrics for a user who only needs a relatively narrow or focused view of the data. You can also share custom dashboards with other users and stakeholders.
According to the [Custom Dashboards - AppDynamics], some of the advantages of the custom dashboard feature are:
It makes drill down across tiers seamless: You can use the grid layout type to create a flexible layout that is easy to rearrange on the canvas. The grid layout also scales in size when viewed on mobile devices. You can also use the absolute layout type to control width and height and the exact placement of widgets on the canvas.
It monitors metrics of interest: You can add widgets from various categories, such as application, server, database, performance, events, and so on. You can also customize the widget properties panel to configure the widget settings, such as title, description, color scheme, time range, auto-refresh interval, and so on.
It schedules dashboard as a report: You can export your custom dashboard as a PDF or HTML report that you can send by email or save as a file. You can also schedule your custom dashboard to run periodically using cron expressions.
Therefore, A (It makes drill down across tiers seamless), C (It monitors metrics of interest), and E (It schedules dashboard as a report) are three advantages of the custom dashboard feature. References:
[Custom Dashboards - AppDynamics]
[Create and Manage Custom Dashboards and Templates - AppDynamics]
Custom Dashboard Permissions - docs.appdynamics.com