The Machine Agent REST API allows you to create custom events that can be used for various purposes in AppDynamics. Some of the reasons you would create custom events using this API are12:

• To create an event to track application deployment. You can use the API to send a custom event that marks the start and end of an application deployment process. This can help you monitor the impact of the deployment on the application performance and availability, as well as correlate any issues or anomalies with the deployment event.
• To create an event to be displayed along with Time Series data in a custom dashboard. You can use the API to send a custom event that contains any relevant information or context that you want to display in a custom dashboard. For example, you can send a custom event that contains the details of a configuration change, a maintenance window, a business transaction, or a user action. You can then use the custom dashboard to visualize the custom event data along with the Time Series data for the metrics you are interested in.
• To create an event to be used to trigger a health rule violation. You can use the API to send a custom event that contains a metric value that you want to use as a condition for a health rule. For example, you can send a custom event that contains the CPU utilization of a machine, and then create a health rule that evaluates the CPU utilization metric and triggers a violation if it exceeds a certain threshold. You can then use the health rule violation to generate alerts, notifications, or remediation actions. References: Machine Agent HTTP Listener, Create Custom Events

According to the Cisco AppDynamics Professional Implementer (CAPI) documents, the two valid ways to confirm that the upgraded Java Agent is running successfully are:

• Verify that the node within the Controller UI indicates the app agent is reporting. (B) This is a valid way because the Controller UI is a web-based application that allows users to monitor and manage the performance of the applications, tiers, nodes, and other entities that are instrumented by the AppDynamics agents. The Controller UI displays the status of the nodes within each tier, and indicates whether the app agent is reporting or not. If the app agent is reporting, the node icon is green and shows the agent version. If the app agent is not reporting, the node icon is gray and shows the last time the agent reported. The user can also hover over the node icon to see more details, such as the agent type, the agent version,the agent runtime directory, and the agent properties file. The user can verify that the upgraded Java Agent is running successfully by checking that the node icon is green and shows the latest agent version12.
• Verify the Java Agent Version metric for that node in the Metric Browser. © This is a valid way because the Metric Browser is a feature of the Controller UI that allows users to view and analyze the metrics collected by the AppDynamics agents. The Metric Browser displays the metrics in a hierarchical tree structure, where each node represents a metric category, a metric name, or a metric value. The user can expand or collapse the nodes, and select or deselect the metrics to view them in a chart. The user can also apply filters, time ranges, baselines, and other options to customize the chart. The user can verify that the upgraded Java Agent is running successfully by navigating to the Java Agent Version metric for that node in the Metric Browser. The Java Agent Version metric shows the version number of the Java Agent that is running on the node. The user can compare the metric value with the expected agent version, and check that the metric is updated after the upgrade34.

The incorrect options are:

• Verify that the application log contains a message indicating success. (A) This is not a valid way because the application log does not contain any message indicating the success of the Java Agent upgrade. The application log is a file that records the events and messages that occur in the application server, such as the startup, shutdown, errors, warnings, and debug information. The application log does not record the events and messages that occur in the Java Agent, such as the installation, upgrade, configuration, or reporting. The Java Agent has its own log file, which is located in the /logs directory, and which contains the messages indicating the success or failure of the Java Agent upgrade .
• Verify that the Java Agent log contains a message indicating the agent started successfully. (D) This is not a valid way because the Java Agent log does not contain any message indicating the agent started successfully after the upgrade. The Java Agent log is a file that records the events and messages that occur in the Java Agent, such as the installation, upgrade, configuration, or reporting. The Java Agent log contains a message indicating the agent started successfully when the application server is started, not when the Java Agent is upgraded. The Java Agent log does not contain any message indicating the success or failure of the Java Agent upgrade. The Java Agent log is located in the /logs directory, and the message indicating the agent started successfully is “Agent Startup Complete” .

References:

• 1: Tiers and Nodes - AppDynamics
• 2: Tier Dashboard - AppDynamics
• 3: Metric Browser - AppDynamics
• 4: Java Agent Metrics - AppDynamics
• [5]: Java Agent Logs - AppDynamics
• [6]: Troubleshoot the Java Agent - AppDynamics

According to the Cisco AppDynamics Professional Implementer (CAPI) documents, the two symptoms that occur if an AppDynamics Controller is not scaled correctly are:

• The Controller’s metric reporting is 7 to 10 minutes behind the current time. (D) This is a valid symptom because the AppDynamics Controller collects, processes, and stores metrics from the agents that monitor the applications, tiers, nodes, and other entities. If the Controller is not scaled correctly, it may not have enough resources, such as CPU, memory,disk space, or network bandwidth, to handle the incoming metrics data. This may result in a backlog of metrics data that causes the Controller to lag behind the current time. The Controller’s metric reporting delay can affect the accuracy and timeliness of the performance analysis and troubleshooting12.
• The Controller UI performs slowly. (E) This is a valid symptom because the AppDynamics Controller UI is a web-based application that allows users to access, visualize, and interact with the performance data and configuration settings of the AppDynamics platform. If the Controller is not scaled correctly, it may not have enough resources, such as CPU, memory, disk space, or network bandwidth, to serve the UI requests. This may result in a slow or unresponsive UI that affects the user experience and productivity12.

The incorrect options are:

• Snapshots are not available after 2 weeks. (A) This is not a valid symptom because the AppDynamics Controller does not store snapshots for more than 2 weeks by default. Snapshots are detailed records of the execution context and call graphs of the business transactions that are monitored by the AppDynamics platform. Snapshots are useful for diagnosing performance issues and errors, but they also consume a lot of disk space. The AppDynamics Controller automatically purges the snapshots that are older than 2 weeks, unless the retention policy is changed by the user. The availability of snapshots is not affected by the Controller scaling, unless the disk space is exhausted34.
• Health rule violations occur more frequently. (B) This is not a valid symptom because the AppDynamics Controller does not cause health rule violations to occur more frequently. Health rule violations are triggered when the performance or availability metrics of the monitored entities exceed the thresholds that are defined by the user. Health rule violations indicate the presence of performance issues or errors in the monitored applications, tiers, nodes, or other entities, not in the Controller itself. The frequency of health rule violations is not affected by the Controller scaling, unless the Controller fails to collect or process the metrics data5 .
• The average response times of tiers are higher than normal. © This is not a valid symptom because the AppDynamics Controller does not affect the average response times of tiers. The average response time of a tier is the average time that the tier takes to process the incoming requests from the business transactions that are monitored by the AppDynamics platform. The average response time of a tier is influenced by the performance and behavior of the application code, the infrastructure, the dependencies, and the workload of the tier, not by the Controller itself. The average response time of a tier is not affected by the Controller scaling, unless the Controller fails to collect or process the metrics data .

References:

• 1: Controller System Requirements - AppDynamics
• 2: Controller Sizing Guidelines - AppDynamics
• 3: Transaction Snapshots - AppDynamics
• 4: Configure Data Retention - AppDynamics
• 5: Health Rules - AppDynamics

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

Before installing an AppDynamics Controller on Linux, you need to perform some preparatory tasks to ensure the system meets the requirements and the installation runs smoothly. Two of these tasks are:

• Install libaio on the host machine if it does not already have it installed. This library facilitates asynchronous I/O operations on the system, which are required by the Controller. You can use the package manager of your Linux distribution to install libaio, such as yum or apt-get. For example, on CentOS, you can run yum install libaio1.
• Verify that you have enough temporary (tmp) space available on the system, at least 1 GB. The Controller installation uses the tmp space to extract and install the software components. You can check the tmp space by running df -h /tmp2. If the tmp space is insufficient, you can either free up some space by deleting unnecessary files, or specify a different temporary directory for the installation by passing the -Djava.io.tmpdir parameter to the installer3.

Other preparatory tasks include verifying the user account permissions, configuring the virus scanners, installing the netstat network utility, and setting the file descriptor limit2. References: Prepare Linux for the Controller, Install the Controller on Linux, and [Controller System Requirements] in the AppDynamics documentation.

The AppDynamics standalone Machine Agent is a Java program that runs on a host machine and collects hardware and infrastructure metrics, such as CPU, memory, disk, and network usage. The Machine Agent can also perform additional functions, such as:

• Acting as a forwarder for analytics events: The Machine Agent can be configured to forward business transaction, log, browser, mobile, and synthetic events from the application agents to the AppDynamics Events Service, which is a distributed, scalable data store for analytics data. The Machine Agent can also forward custom events from the SDK or API to the Events Service. This allows you to use the AppDynamics Analytics features, such as dashboards, queries, funnels, and metrics, to analyze the performance and behavior of your applications and users12.
• Starting an HTTP listener for custom metrics: The Machine Agent can be configured to start an HTTP listener that can receive custom metrics from external sources, such as scripts, tools, or other applications. The Machine Agent can then report these custom metrics to the AppDynamics Controller, where youcan view them in the Metric Browser or use them in health rules, policies, or dashboards. This allows you to monitor any aspect of your system that is not covered by the default Machine Agent metrics34.

The other statements are false because:

• B. The Machine Agent cannot send SNMP alerts. The Machine Agent can only receive SNMP traps from external sources and report them as events to the AppDynamics Controller. The AppDynamics Controller can send SNMP alerts to external systems based on health rule violations or events, but this is not a function of the Machine Agent5 .
• C. The Machine Agent cannot communicate with multiple AppDynamics Controllers. The Machine Agent can only communicate with one Controller at a time, which is specified in the controller-info.xml file in the agent configuration directory. If you want to monitor the same host machine with multiple Controllers, you need to install multiple Machine Agents on the same machine, each with a different Controller configuration and port number .
• D. The Machine Agent cannot restart itself if it goes down. The Machine Agent does not have a built-in mechanism to automatically restart itself in case of a failure or a crash. You need to use an external tool or script to monitor the Machine Agent process and restart it if necessary. Alternatively, you can use the AppDynamics Agent Installer to deploy the Machine Agent as a service, which can be configured to restart automatically on failure .

References: Analytics Agent, Analytics Data, HTTP Listener, Custom Metrics, SNMP Trap Alerting Integration, [SNMP Integration], [Machine Agent Configuration Properties], [Install the Machine Agent], [Agent Installer], [Start and Stop the Machine Agent]

According to the Cisco AppDynamics Professional Implementer (CAPI) documents, the two reasons that would require an administrator to install the Events Service cluster manually are:

• Security concerns with passwordless SSH (B): This is a valid reason because the automated installation of the Events Service cluster requires passwordless SSH access to the target hosts. Passwordless SSH allows the Enterprise Console to execute commands on the remote hosts without prompting for a password. However, some organizations may have security policies that prohibit passwordless SSH access, as it may pose a risk of unauthorized access or malicious attacks. In such cases, the administrator can install the Events Service cluster manually, by following the steps described in the Manual Installation of the Events Service Cluster document1.
• Security requirements to install using a non-root user account ©: This is a valid reason because the automated installation of the Events Service cluster requires root privileges on the target hosts. Root privileges allow the Enterprise Console to create directories, change permissions, and install packages on the remote hosts. However, some organizations may have security policies that restrict root access, as it may pose a risk of accidental or intentional damage to the system. In such cases, the administrator can install the Events Service cluster manually, by following the steps described in the Manual Installation of the Events Service Cluster document1. The administrator can use a non-root user account that has sudo privileges to perform the manual installation.

The incorrect options are:

• Installation on SUSE Linux (A): This is not a valid reason for manual installation, because the automated installation of the Events Service cluster supports SUSE Linux as one of the compatible operating systems. The Enterprise Console can install the Events Service cluster on SUSE Linux hosts using the automated installation process, as long as the hosts meet the prerequisites described in the Events Service Requirements document2.
• Installation on Windows (D): This is not a valid reason for manual installation, because the Events Service cluster does not support Windows as an operating system. The Events Service cluster can only run on Linux hosts, as it is based on Apache Cassandra, which is a Linux-based distributed database. The Events Service cluster cannot be installed on Windows hosts, either manually or automatically2.

References:

• 1: Manual Installation of the Events Service Cluster - AppDynamics
• 2: Events Service Requirements - AppDynamics