Monitoring and Troubleshooting

1. A developer needs to track the number of failed login attempts in an application running on Amazon EC2. Which approach provides the most real-time visibility into this specific application-level metric?

• A.Use the CloudWatch agent to monitor the standard AWS/EC2 namespace for failed login attempts.
• B.Instrument the application code to call the CloudWatch PutMetricData API whenever a login fails.✓ Correct
• C.Write the failed login attempts to a local file and configure an AWS Lambda function to poll the file.
• D.Enable detailed monitoring on the EC2 instance to automatically capture application-specific custom metrics.

2. A development team is publishing a custom metric using the CloudWatch PutMetricData API. They want to ensure they can aggregate the data across different customer tiers (e.g., Free, Pro, Enterprise). How should they structure the metric data?

• A.Create separate namespaces for each customer tier to ensure metrics are logically isolated.
• B.Include a Dimension array in the PutMetricData request with a Key of 'Tier' and a Value of the customer's tier.✓ Correct
• C.Append the customer tier to the metric name, creating unique metric names like 'ActiveUsers_Pro'.
• D.Use the Unit parameter to define the customer tier so that CloudWatch automatically groups them.

3. An application writes error logs to a custom log file on an Amazon EC2 instance. A developer wants to track the frequency of 'NullReferenceException' occurrences and view this as a graph in CloudWatch. What is the most efficient way to achieve this?

• A.Install the CloudWatch agent to push logs to CloudWatch Logs, then create a metric filter to match the exception string.✓ Correct
• B.Write a cron job that greps the log file every minute and calls the PutMetricData API with the count.
• C.Configure the EC2 instance metadata service to automatically stream all local files to CloudWatch metrics.
• D.Use AWS X-Ray to parse the application log file and generate a custom time-series graph based on error strings.

4. A developer wants to centralize application logs from several Amazon EC2 instances into Amazon CloudWatch Logs. Which sequence of steps is required to implement this solution?

• A.Enable detailed monitoring on the EC2 instances and specify the log group name in the EC2 user data.
• B.Attach an IAM role with CloudWatch Logs permissions to the instances and configure the CloudWatch agent.✓ Correct
• C.Configure an Amazon S3 bucket for log delivery and use Athena to query the logs directly into CloudWatch.
• D.Modify the application code to use the AWS SDK to send logs directly to AWS CloudTrail.

5. An application's custom metric tracks the queue length of a background processing system. When the queue length exceeds 1000 items for 3 consecutive minutes, the development team needs to be notified via email. How should this be configured?

• A.Create a CloudWatch Logs Insights query that sends an email when the queue length reaches the specified limit.
• B.Configure a CloudWatch metric filter to trigger an AWS Lambda function that sends an email via Amazon SES.
• C.Create a CloudWatch Alarm based on the custom metric and configure its action to publish to an Amazon SNS topic.✓ Correct
• D.Set up an AWS Auto Scaling lifecycle hook to pause the application and email the team when the queue is full.