Minimum, maximum, and desired capacity in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Auto Scaling Group Capacity Settings

An Auto Scaling Group (ASG) in AWS has the following settings:

• Minimum capacity: 2
• Maximum capacity: 5
• Desired capacity: 4

What happens if the desired capacity is set to 6?

A The ASG will launch 6 instances, exceeding the maximum capacity.

B The ASG will launch 5 instances, respecting the maximum capacity limit.

C The ASG will launch 4 instances, ignoring the desired capacity change.

D The ASG will shut down instances to maintain the minimum capacity.

💡 Hint

Remember that the maximum capacity limits the number of instances the ASG can have.

The desired capacity cannot exceed the maximum capacity. If you set desired capacity to 6 but maximum is 5, the ASG will launch only 5 instances.

❓ service_behavior

intermediate

Behavior When Desired Capacity is Lower Than Minimum Capacity

An Auto Scaling Group has minimum capacity 3, maximum capacity 6, and desired capacity 4.

What happens if you set the desired capacity to 2?

A The ASG will launch 3 instances, respecting the minimum capacity.

B The ASG will launch 2 instances, below the minimum capacity.

C The ASG will launch 4 instances, ignoring the desired capacity change.

D The ASG will shut down all instances.

💡 Hint

The minimum capacity is the lowest number of instances the ASG maintains.

The ASG will not go below the minimum capacity. Setting desired capacity below minimum causes the ASG to maintain the minimum number of instances.

❓ Architecture

advanced

Designing an Auto Scaling Group for Variable Traffic

You want to design an Auto Scaling Group that can handle traffic spikes up to 10 instances but normally runs with 3 instances. The minimum capacity should ensure availability, and the maximum capacity should prevent excessive costs.

Which configuration best fits this requirement?

A Minimum capacity: 3, Desired capacity: 3, Maximum capacity: 10

B Minimum capacity: 10, Desired capacity: 3, Maximum capacity: 10

C Minimum capacity: 3, Desired capacity: 10, Maximum capacity: 10

D Minimum capacity: 1, Desired capacity: 3, Maximum capacity: 10

💡 Hint

Minimum capacity should ensure availability during low traffic.

Setting minimum capacity to 3 ensures at least 3 instances always run. Desired capacity 3 matches normal load. Maximum 10 allows scaling up during spikes.

❓ security

advanced

Security Implications of Auto Scaling Group Capacity Settings

An Auto Scaling Group is configured with minimum capacity 0, desired capacity 0, and maximum capacity 5. What is a potential security risk of this configuration?

A The ASG will always run 5 instances, increasing attack surface.

B No instances will run, so the application is unavailable and secure.

C Instances may launch unexpectedly if scaling policies trigger, possibly exposing unpatched instances.

D The ASG will shut down instances randomly, causing security alerts.

💡 Hint

Think about what happens when scaling policies trigger from zero instances.

With minimum and desired capacity zero, no instances run initially. But scaling policies can launch instances automatically, which if not properly secured or patched, can expose vulnerabilities.

✅ Best Practice

expert

Optimizing Auto Scaling Group Capacity for Cost and Performance

You manage an Auto Scaling Group with minimum capacity 2, maximum capacity 8, and desired capacity 5. You want to optimize for cost without sacrificing performance during peak hours.

Which strategy is best?

A Set desired capacity to 8 permanently to handle all peaks without scaling.

B Set maximum capacity to 2 to reduce costs and rely on instance performance.

C Disable scaling policies to keep capacity fixed at desired value.

D Set minimum capacity to 5 during peak hours and 2 during off-peak hours using scheduled scaling.

💡 Hint

Think about adjusting capacity based on predictable traffic patterns.

Scheduled scaling allows adjusting minimum capacity to meet peak demand and reduce costs during off-peak times by lowering minimum capacity.