CloudWatch metrics in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

Understanding CloudWatch Metric Retention Periods

CloudWatch stores metrics with different retention periods depending on the granularity. Which of the following correctly describes the retention period for 1-minute metrics?

A 1-minute metrics are retained for 15 days.

B 1-minute metrics are retained for 455 days.

C 1-minute metrics are retained for 63 days.

D 1-minute metrics are retained indefinitely.

💡 Hint

Think about how CloudWatch stores detailed metrics before aggregating them.

CloudWatch retains 1-minute metrics for 63 days. After that, it aggregates data into 5-minute and 1-hour metrics with longer retention.

❓ Architecture

intermediate

Choosing Metric Granularity for Cost and Detail

You want to monitor an application with detailed metrics but keep CloudWatch costs low. Which metric granularity should you choose to balance detail and cost?

A Use 1-second custom metrics for all data points.

B Use 1-minute standard metrics for most data points.

C Use 5-minute standard metrics for all data points.

D Use 1-hour aggregated metrics only.

💡 Hint

Consider the default granularity and cost implications.

1-minute standard metrics provide detailed monitoring with reasonable cost. 1-second metrics are expensive and usually unnecessary.

❓ security

advanced

Securing CloudWatch Metrics Access

You want to restrict access so that a user can only view CloudWatch metrics for a specific EC2 instance. Which IAM policy condition correctly enforces this?

AWS

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Action": ["cloudwatch:GetMetricData"],
    "Resource": "*",
    "Condition": {
      "StringEquals": {
        "cloudwatch:dimension_InstanceId": "i-1234567890abcdef0"
      }
    }
  }]
}

A Use a condition with "ec2:InstanceId" matching the EC2 instance ID.

B Use a resource ARN restricting to the EC2 instance ARN.

C Use a condition with "cloudwatch:Namespace" set to "AWS/EC2".

D Use a condition with "cloudwatch:dimension_InstanceId" matching the EC2 instance ID.

💡 Hint

CloudWatch metrics can be filtered by dimensions in IAM conditions.

The correct way is to use the condition key "cloudwatch:dimension_InstanceId" to restrict metric access to the specific EC2 instance.

❓ Configuration

advanced

Configuring Custom Metrics with Dimensions

You want to publish a custom metric to CloudWatch with two dimensions: "ServiceName" and "Environment". Which of the following JSON payloads correctly represents this metric data?

A { "MetricName": "RequestCount", "Dimensions": [{"Name": "ServiceName", "Value": "Auth"}, {"Name": "Environment", "Value": "Prod"}], "Value": 100 }

B { "MetricName": "RequestCount", "Dimension": [{"Name": "ServiceName", "Value": "Auth"}, {"Name": "Environment", "Value": "Prod"}], "Value": 100 }

C { "MetricName": "RequestCount", "Dimensions": {"ServiceName": "Auth", "Environment": "Prod"}, "Value": 100 }

D { "MetricName": "RequestCount", "Dimensions": [{"ServiceName": "Auth"}, {"Environment": "Prod"}], "Value": 100 }

💡 Hint

Check the correct key names and structure for dimensions in CloudWatch metric data.

The key must be "Dimensions" (plural) and each dimension is an object with "Name" and "Value" keys inside an array.

🧠 Conceptual

expert

Interpreting CloudWatch Metric Math Output

You have two CloudWatch metrics: CPUUtilization and NetworkIn. You create a metric math expression: CPUUtilization / NetworkIn. If NetworkIn is zero at some points, what will be the output of the expression at those points?

A The output will be null (no data) for those points.

B The output will be infinity (∞) for those points.

C The output will be zero to avoid division errors.

D The output will cause the entire metric math query to fail.

💡 Hint

Think about how CloudWatch handles division by zero in metric math.

CloudWatch metric math returns null (no data) for points where division by zero would occur, avoiding errors or infinite values.