The answer is to add more EC2 instances to the Auto Scaling group, add read replicas to ElastiCache, and enable ELB connection draining. Scaling out horizontally distributes the increased request load across more compute resources, while adding ElastiCache read replicas offloads read-heavy session lookups from the primary Redis node, directly addressing the root cause of peak-hour latency. Enabling connection draining on the ALB ensures that in-flight requests complete gracefully during instance rotations, preventing dropped sessions and maintaining zero downtime. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your ability to distinguish between horizontal scaling and vertical scaling—a common trap is choosing “increase instance size,” which can cause downtime without a rolling replacement strategy. Remember the mnemonic “HARD”: Horizontal scaling, Add read replicas, Remove downtime with draining.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application stores session state in an Amazon ElastiCache Redis cluster. The operations team has noticed that during peak hours, application response times increase significantly. They need to improve performance without downtime. Which THREE actions should they take? (Choose 3)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable connection draining on the ALB.
Option A: Adding more EC2 instances scales horizontally, distributing load. Option B: Increasing instance size vertical scaling may cause downtime if done without rolling replacement. Option C: Adding read replicas to ElastiCache offloads read traffic. Option D: Enabling ELB connection draining ensures in-flight requests complete during instance replacement, improving availability. Option B is not chosen because it can cause downtime.
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.
✓
Enable connection draining on the ALB.
Why this is correct
Connection draining allows existing connections to complete before instances are deregistered, improving availability during scaling events.
Related concept
Read the scenario before looking for a memorised answer.
✗
Decrease the idle timeout of the ALB.
Why it's wrong here
Decreasing idle timeout may cause premature disconnection, degrading user experience.
✗
Increase the EC2 instance size to a larger instance type.
Why it's wrong here
Vertical scaling often requires stopping instances, causing downtime.
✓
Add read replicas to the ElastiCache Redis cluster.
Why this is correct
Read replicas offload read requests from the primary node, improving performance.
Related concept
Read the scenario before looking for a memorised answer.
✓
Add more EC2 instances to the Auto Scaling group.
Why this is correct
Horizontal scaling distributes load and improves responsiveness without downtime.
Related concept
Read the scenario before looking for a memorised answer.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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.
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: Enable connection draining on the ALB. — Option A: Adding more EC2 instances scales horizontally, distributing load. Option B: Increasing instance size vertical scaling may cause downtime if done without rolling replacement. Option C: Adding read replicas to ElastiCache offloads read traffic. Option D: Enabling ELB connection draining ensures in-flight requests complete during instance replacement, improving availability. Option B is not chosen because it can cause downtime.
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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Question Discussion
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