You are a DevOps engineer in a financial company. In order to meet an ongoing compliance audit in the company, you need to set up CloudWatch alarms for the key AWS resources in production including EC2, DynamoDB, Lambda, etc. To save time, you plan to create CloudWatch alarms based on existing CloudWatch Metrics. Which scenarios are suitable for this? (Select TWO.)

Answer options:

A.When the latency of ELB exceeds 10 seconds over two minutes, trigger an alarm and send an email notification to your team.
B.When someone in the development team has provided comments on commit or pull requests in AWS CodeCommit service, notify relevant team members.
C.Notify the team when excessive throttling occurs for a DynamoDB table that stores users’ subscription data.
D.When the average EC2 instance memory usage exceeds 95 percent for five minutes, trigger an alarm and launch another EC2 instance.
E.When there are some critical Tomcat errors happening in EC2 instances, immediately send an SMS to the on-call support.

Correct Answer – A, C
The key for this question is that it requires existing CloudWatch Metrics, which means that customized Metrics are not allowed. Other services such as CloudWatch Events or CloudWatch Logs should not be selected as well.
Option A is CORRECT: Because ELB has provided an Average Latency Metrics that can be used to set up a CloudWatch alarm:
Option B is incorrect: Because this should be a use case for CloudWatch Events rather than CloudWatch Alarms:
Option C is CORRECT: Because DynamoDB table has supported the CloudWatch Metrics of throttled read/write events or requests.
Option D is incorrect: Because EC2 instance memory usage is a customized metric that is not natively provided by CloudWatch.
Option E is incorrect: Because CloudWatch EC2 Metrics do not trace detailed application status such as Tomcat error. This is a use case for customized CloudWatch Logs and an alarm can be created via a Logs Metric Filter.