Right-sizing resources in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Right-Sizing Benefits

Which of the following is the primary benefit of right-sizing cloud resources?

A Avoiding any monitoring of resource usage

B Increasing the number of resources regardless of workload

C Maximizing resource usage by always running at full capacity

D Reducing costs by matching resource capacity to actual workload needs

💡 Hint

Think about how using only what you need affects your bill.

Right-sizing means adjusting resources to fit the workload, which helps reduce unnecessary costs.

❓ Architecture

intermediate

Choosing the Right EC2 Instance Type

You have a web application with variable traffic that spikes during business hours. Which EC2 instance type strategy best supports right-sizing?

A Use a fixed large instance 24/7 to handle peak load

B Use the smallest instance type and manually upgrade when needed

C Use auto-scaling groups with smaller instances that scale out during peak times

D Use spot instances only without any scaling

💡 Hint

Consider how to handle changing traffic efficiently.

Auto-scaling with smaller instances allows the system to adjust capacity dynamically, matching demand and saving costs.

❓ Configuration

advanced

Analyzing CloudWatch Metrics for Right-Sizing

Given the following CloudWatch CPU utilization data for an EC2 instance over a week, which action best represents right-sizing?

Average CPU Utilization: 10%

A Downsize the instance to a smaller type to reduce costs

B Keep the instance size the same since utilization is stable

C Terminate the instance immediately

D Increase the instance size to handle more load

💡 Hint

Low CPU usage suggests the instance might be over-provisioned.

Low average CPU utilization indicates the instance is larger than needed, so downsizing saves money without impacting performance.

❓ security

advanced

Right-Sizing and Security Implications

When right-sizing resources, which security consideration is most important?

A Using default open firewall rules to simplify access

B Ensuring smaller instances have the same security groups and patches as larger ones

C Removing all security controls to improve performance on smaller instances

D Disabling encryption to reduce CPU load

💡 Hint

Think about maintaining security standards regardless of resource size.

Right-sizing should not reduce security; smaller instances must maintain the same protections as larger ones.

❓ service_behavior

expert

Impact of Right-Sizing on Auto Scaling Behavior

You have an Auto Scaling group with instances of type t3.large. After analyzing usage, you downsize to t3.medium instances. What is the expected impact on the Auto Scaling group's behavior?

A The group will launch more instances to maintain the same total capacity during scale-out events

B The group will launch fewer instances because each is smaller

C The group will stop scaling automatically until manually restarted

D The group will automatically upgrade instances back to t3.large

💡 Hint

Consider how instance size affects the number of instances needed to handle load.

Smaller instances provide less capacity, so the Auto Scaling group will launch more instances to meet demand.

Practice

1. What does right-sizing mean in cloud resource management?

easy

A. Always picking the largest resource available

B. Choosing the best resource size to match your actual needs

C. Using resources without monitoring their usage

D. Ignoring cost and focusing only on performance

Solution

1. Step 1: Understand the meaning of right-sizing

   Right-sizing means selecting resources that fit your workload requirements without waste.

2. Step 2: Compare options to definition

   Only Choosing the best resource size to match your actual needs matches the idea of matching resource size to actual needs.

3. Final Answer:

   Choosing the best resource size to match your actual needs -> Option B

4. Quick Check:

   Right-sizing = best fit resource size [OK]

Hint: Right-sizing means matching size to need, not max or ignore usage [OK]

Common Mistakes:

• Thinking right-sizing means always picking the biggest resource
• Ignoring usage data when choosing resources
• Confusing right-sizing with ignoring costs

2. Which AWS service helps you analyze resource usage to right-size your EC2 instances?

easy

A. AWS CloudTrail

B. AWS Cost Explorer

C. AWS Trusted Advisor

D. AWS Lambda

Solution

1. Step 1: Identify AWS services for resource optimization

   AWS Trusted Advisor provides recommendations including right-sizing EC2 instances.

2. Step 2: Eliminate unrelated services

   CloudTrail logs API calls, Cost Explorer shows costs, Lambda runs code; only Trusted Advisor analyzes usage for right-sizing.

3. Final Answer:

   AWS Trusted Advisor -> Option C

4. Quick Check:

   Trusted Advisor = right-sizing help [OK]

Hint: Trusted Advisor gives right-sizing tips for EC2 [OK]

Common Mistakes:

• Confusing CloudTrail with usage analysis
• Thinking Cost Explorer directly suggests right-sizing
• Selecting Lambda which is unrelated to resource sizing

3. You have an EC2 instance running at 10% CPU most of the time. What is the likely output of a right-sizing recommendation script?

medium

A. Recommend upgrading to a larger instance type

B. Recommend no change to instance size

C. Recommend terminating the instance

D. Recommend downgrading to a smaller instance type

Solution

1. Step 1: Analyze CPU usage data

   10% CPU usage means the instance is underutilized and likely oversized.

2. Step 2: Determine right-sizing action

   Underutilization suggests downgrading to a smaller instance to save cost.

3. Final Answer:

   Recommend downgrading to a smaller instance type -> Option D

4. Quick Check:

   Low CPU usage = downsize instance [OK]

Hint: Low CPU means smaller instance recommended [OK]

Common Mistakes:

• Choosing to upgrade when usage is low
• Thinking no change is needed despite low usage
• Confusing termination with right-sizing

4. A user tries to right-size an EC2 instance but gets an error: "Instance type not supported in this AZ." What is the best fix?

medium

A. Change the instance type to one supported in the availability zone

B. Ignore the error and try again

C. Terminate the instance immediately

D. Switch to a different AWS region without checking

Solution

1. Step 1: Understand the error context

   The error means the chosen instance type is not available in the current availability zone.

2. Step 2: Apply correct fix

   Selecting an instance type supported in the same availability zone resolves the error.

3. Final Answer:

   Change the instance type to one supported in the availability zone -> Option A

4. Quick Check:

   Unsupported instance type in AZ = pick supported type [OK]

Hint: Pick instance types supported in your AZ [OK]

Common Mistakes:

• Ignoring the error and retrying
• Terminating instance without fixing
• Switching regions without checking availability

5. You manage a fleet of EC2 instances with varying CPU usage. Which approach best applies right-sizing to reduce costs without hurting performance?

hard

A. Start with smallest instance types, monitor usage, then scale up as needed

B. Always pick the largest instance type to avoid performance issues

C. Randomly change instance types monthly without monitoring

D. Terminate all instances and switch to on-demand only

Solution

1. Step 1: Understand right-sizing best practice

   Right-sizing means starting small and adjusting based on real usage data to avoid waste.

2. Step 2: Evaluate options for cost and performance balance

   Start with smallest instance types, monitor usage, then scale up as needed follows best practice by starting small, monitoring, and scaling up only if needed.

3. Final Answer:

   Start with smallest instance types, monitor usage, then scale up as needed -> Option A

4. Quick Check:

   Start small + monitor + scale = right-sizing [OK]

Hint: Start small, watch usage, then adjust size [OK]

Common Mistakes:

• Always picking largest instance wastes money
• Changing types randomly causes instability
• Terminating all instances ignores workload needs