- A
Increase the minimum size of the Auto Scaling group to 10 to handle the surge without scaling down.
Why wrong: This would increase cost and does not solve the session loss on instance termination during scale-in.
- B
Disable stickiness on the ALB so that any instance can handle any request.
Why wrong: Without stickiness, sessions would be lost even without scaling, as requests are distributed randomly.
- C
Modify the application to store session data in an Amazon ElastiCache for Redis cluster instead of local ephemeral storage.
This decouples sessions from instances, making them persistent across scaling events and instance replacements.
- D
Increase the health check interval on the ALB to prevent instances from being marked unhealthy too quickly.
Why wrong: This does not address session storage; sessions are still lost when instances are terminated.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company runs a critical e-commerce platform on AWS. The application consists of an Application Load Balancer (ALB) that distributes traffic to an Auto Scaling group of EC2 instances running a web server. The web servers store session data locally on the instance's ephemeral storage. The Auto Scaling group is configured with a min of 2, max of 10, and desired of 2. Recently, during a flash sale, traffic surged and the Auto Scaling group scaled out to 10 instances. However, many users reported that their shopping carts were lost and they were logged out during the event. The Cognito user pool was used for authentication, and the application uses cookies to maintain session state. The ALB's stickiness is enabled. The team observed that the ALB's RequestCountPerTarget metric was well below the instance's capacity, but the error rate increased. The CloudWatch logs show that the web server returned 503 errors for a subset of requests. After the flash sale ended, the Auto Scaling group scaled back to 2 instances, and the issue disappeared. The team wants to prevent this from happening in future events. Which solution should the Solutions Architect recommend?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Modify the application to store session data in an Amazon ElastiCache for Redis cluster instead of local ephemeral storage.
The root cause is that session data stored on ephemeral storage is lost when instances are terminated or replaced. Even with ALB stickiness, if an instance is terminated (e.g., due to scaling in or health check failure), the session data is gone. Option C solves this by storing sessions externally in ElastiCache, which persists independently of EC2 instances, ensuring sessions survive scaling events. Option A would prevent scaling in but does not address data loss if instances become unhealthy or replaced. Option B would make the problem worse because without stickiness, requests could go to different instances, causing session loss even without termination. Option D only delays health checks and does not solve data loss.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the minimum size of the Auto Scaling group to 10 to handle the surge without scaling down.
Why it's wrong here
This would increase cost and does not solve the session loss on instance termination during scale-in.
- ✗
Disable stickiness on the ALB so that any instance can handle any request.
Why it's wrong here
Without stickiness, sessions would be lost even without scaling, as requests are distributed randomly.
- ✓
Modify the application to store session data in an Amazon ElastiCache for Redis cluster instead of local ephemeral storage.
Why this is correct
This decouples sessions from instances, making them persistent across scaling events and instance replacements.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the health check interval on the ALB to prevent instances from being marked unhealthy too quickly.
Why it's wrong here
This does not address session storage; sessions are still lost when instances are terminated.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
What to study next
Got this wrong? Here's your next step.
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Continuous Improvement for Existing Solutions — study guide chapter
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FAQ
Questions learners often ask
What does this SAP-C02 question test?
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the application to store session data in an Amazon ElastiCache for Redis cluster instead of local ephemeral storage. — The root cause is that session data stored on ephemeral storage is lost when instances are terminated or replaced. Even with ALB stickiness, if an instance is terminated (e.g., due to scaling in or health check failure), the session data is gone. Option C solves this by storing sessions externally in ElastiCache, which persists independently of EC2 instances, ensuring sessions survive scaling events. Option A would prevent scaling in but does not address data loss if instances become unhealthy or replaced. Option B would make the problem worse because without stickiness, requests could go to different instances, causing session loss even without termination. Option D only delays health checks and does not solve data loss.
What should I do if I get this SAP-C02 question wrong?
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 20, 2026
This SAP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAP-C02 exam.
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