Default vs custom metrics in AWS - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Default Metrics in AWS CloudWatch

Which of the following statements correctly describes AWS CloudWatch default metrics?

A Default metrics only include custom application logs sent to CloudWatch.

B Default metrics require manual setup and are charged per metric collected.

C Default metrics are automatically collected for AWS services without extra configuration and are available at no additional cost.

D Default metrics are only available for EC2 instances and not for other AWS services.

💡 Hint

Think about what AWS provides out-of-the-box for monitoring without extra setup.

AWS CloudWatch provides default metrics automatically for many AWS services like EC2, RDS, and ELB. These metrics are collected without extra configuration and do not incur additional charges.

❓ service_behavior

intermediate

Behavior of Custom Metrics in AWS CloudWatch

What happens when you publish a custom metric to AWS CloudWatch?

A The metric is stored, but you are charged based on the number of metrics and data points published.

B The metric is stored and available immediately with no charges applied.

C The metric replaces any default metrics with the same name automatically.

D The metric is only stored locally on the instance and not visible in CloudWatch.

💡 Hint

Consider AWS pricing for custom monitoring data.

Custom metrics in CloudWatch are stored and visible like default metrics, but AWS charges based on the number of custom metrics and data points you publish.

❓ Architecture

advanced

Designing Monitoring with Default and Custom Metrics

You want to monitor an application running on EC2 instances. You need CPU usage, memory usage, and a custom business metric. Which approach is best?

A Use default metrics for business data and custom metrics for CPU and memory.

B Create custom metrics for CPU, memory, and business data to have consistent data sources.

C Use only default metrics since they cover CPU and memory usage automatically.

D Use default CloudWatch metrics for CPU and create a custom metric for memory and business data.

💡 Hint

Remember which metrics AWS collects by default and which require custom setup.

CloudWatch provides CPU usage as a default metric for EC2, but memory usage is not collected by default and requires a custom metric. Business-specific data also requires custom metrics.

❓ security

advanced

Security Considerations for Custom Metrics in AWS CloudWatch

Which of the following is a best practice to secure custom metrics data sent to CloudWatch?

A Use IAM roles with least privilege to allow only necessary metric publishing permissions.

B Allow all EC2 instances to publish metrics to CloudWatch without restrictions for simplicity.

C Send custom metrics over unencrypted HTTP to reduce latency.

D Store custom metrics data locally on instances to avoid exposing data in CloudWatch.

💡 Hint

Think about AWS security best practices for permissions and data transmission.

Using IAM roles with least privilege ensures only authorized entities can publish custom metrics. Data should be sent securely, and unrestricted permissions increase risk.

✅ Best Practice

expert

Cost Optimization with Default and Custom Metrics

Your application generates many custom metrics, causing high CloudWatch costs. Which strategy best reduces costs while maintaining monitoring quality?

A Delete all custom metrics and rely only on default metrics regardless of monitoring needs.

B Aggregate multiple related custom metrics into fewer metrics using dimensions and statistics.

C Increase the frequency of custom metric publishing to get more detailed data.

D Publish all metrics as separate custom metrics without aggregation for clarity.

💡 Hint

Think about how to reduce the number of metrics without losing important information.

Aggregating related metrics using dimensions and statistics reduces the number of custom metrics and data points, lowering costs while keeping monitoring effective.

Practice

1. Which statement best describes AWS default metrics in CloudWatch?

easy

A. They are automatically collected and free within certain limits.

B. They require manual setup and extra charges.

C. They only track custom application data.

D. They are disabled by default and need activation.

Solution

1. Step 1: Understand default metrics collection

   AWS CloudWatch automatically collects default metrics for many services without extra setup.

2. Step 2: Recognize cost and availability

   These default metrics are free within certain usage limits, making them easy to use.

3. Final Answer:

   They are automatically collected and free within certain limits. -> Option A

4. Quick Check:

   Default metrics = automatic + free [OK]

Hint: Default metrics are automatic and free within limits [OK]

Common Mistakes:

• Thinking default metrics need manual setup
• Assuming default metrics track custom data
• Believing default metrics are disabled by default

2. Which of the following is the correct way to send a custom metric to AWS CloudWatch using the AWS CLI?

easy

A. aws cloudwatch send-metric --name CPUUtilization --value 70

B. aws cloudwatch add-metric-data --metric-name CPUUtilization --value 70

C. aws cloudwatch create-metric --metric CPUUtilization --value 70

D. aws cloudwatch put-metric-data --metric-name CPUUtilization --namespace AWS/EC2 --value 70

Solution

1. Step 1: Identify the correct AWS CLI command

   The correct command to send custom metric data is put-metric-data under aws cloudwatch.

2. Step 2: Check the syntax and parameters

   The command requires --metric-name, --namespace, and --value parameters as shown in aws cloudwatch put-metric-data --metric-name CPUUtilization --namespace AWS/EC2 --value 70.

3. Final Answer:

   aws cloudwatch put-metric-data --metric-name CPUUtilization --namespace AWS/EC2 --value 70 -> Option D

4. Quick Check:

   Use put-metric-data with metric-name and namespace [OK]

Hint: Use 'put-metric-data' with metric-name and namespace [OK]

Common Mistakes:

• Using incorrect command names like send-metric or create-metric
• Omitting the namespace parameter
• Confusing metric creation with data sending

3. Given the following AWS CloudWatch custom metric data sent every minute:

aws cloudwatch put-metric-data --metric-name PageViews --namespace MyApp --value 5

What will be the average value shown in CloudWatch after 3 minutes if the command is run 3 times with values 5, 7, and 8 respectively?

medium

A. 6.67

B. 7

C. 20

D. 5

Solution

1. Step 1: Sum the metric values sent

   The values sent are 5, 7, and 8. Their sum is 5 + 7 + 8 = 20.

2. Step 2: Calculate the average over 3 data points

   Average = Total sum / Number of data points = 20 / 3 ≈ 6.67.

3. Final Answer:

   6.67 -> Option A

4. Quick Check:

   Average = sum/3 = 6.67 [OK]

Hint: Average = sum of values divided by count [OK]

Common Mistakes:

• Adding values but not dividing by count
• Taking the last value as average
• Multiplying values instead of averaging

4. You tried to send a custom metric to CloudWatch but it does not appear in the console. Which of the following is the most likely cause?

medium

A. CloudWatch only shows metrics after 24 hours delay.

B. You forgot to specify the metric namespace in the command.

C. Custom metrics are automatically visible without sending data.

D. Default metrics do not require namespaces, so this is normal.

Solution

1. Step 1: Check required parameters for custom metrics

   Custom metrics require a namespace to organize and display them properly in CloudWatch.

2. Step 2: Understand impact of missing namespace

   If the namespace is missing, CloudWatch cannot categorize the metric, so it won't appear in the console.

3. Final Answer:

   You forgot to specify the metric namespace in the command. -> Option B

4. Quick Check:

   Missing namespace hides custom metric [OK]

Hint: Always specify namespace when sending custom metrics [OK]

Common Mistakes:

• Assuming default metrics need namespaces
• Expecting immediate visibility without data sent
• Believing CloudWatch delays metric display by 24 hours

5. You want to monitor a custom application metric that tracks the number of user logins per hour. The default AWS metrics do not provide this data. What is the best approach to achieve this?

hard

A. Enable detailed monitoring on EC2 instances to get user login data.

B. Use the default CPUUtilization metric to estimate user logins.

C. Send custom metric data for user logins to CloudWatch using a unique namespace and metric name.

D. Create an alarm on default network metrics to infer user logins.

Solution

1. Step 1: Identify the need for custom data

   User logins per hour is specific to the application and not tracked by default AWS metrics.

2. Step 2: Use custom metrics for application-specific data

   Sending custom metric data with a unique namespace and metric name allows tracking exactly this information in CloudWatch.

3. Final Answer:

   Send custom metric data for user logins to CloudWatch using a unique namespace and metric name. -> Option C

4. Quick Check:

   Custom metrics track app-specific data [OK]

Hint: Use custom metrics for app-specific tracking [OK]

Common Mistakes:

• Trying to use unrelated default metrics for app data
• Assuming detailed monitoring tracks application events
• Using alarms on unrelated metrics to guess user activity