The correct choice is to change the instance type to a smaller size, such as db.t3.medium, while keeping Multi-AZ enabled. This directly addresses over-provisioned downsizing cost optimization by selecting a more appropriately sized instance for the consistently low CPU and memory usage, while retaining Multi-AZ ensures high availability is not sacrificed. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding that RDS instance resizing is a live, online operation for Multi-AZ deployments, and the common trap is assuming you must disable Multi-AZ to change the instance type or that Reserved Instances are a better immediate fix. Remember the memory tip: "Downsize the size, keep the AZ pair" — you can always scale down the instance class without touching the Multi-AZ configuration, and only a brief failover occurs during the modification.
SOA-C02 Cost and Performance Optimization Practice Question
This SOA-C02 practice question tests your understanding of cost and performance optimization. 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 production database on a db.r5.large RDS instance with Multi-AZ enabled. They notice that the CPU utilization is consistently below 10% and memory usage is below 20%. The application is not expected to grow significantly. Which action would optimize costs without sacrificing high availability?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the instance type to a smaller size, such as db.t3.medium, and keep Multi-AZ.
Option C is correct because the instance is over-provisioned; downsizing to a smaller instance type (e.g., db.r5.large to db.t3.medium) reduces cost. Multi-AZ should be retained for high availability. Option A is wrong because removing Multi-AZ sacrifices high availability. Option B is wrong because Reserved Instances require a commitment and may not be cost-effective if the instance type is changed. Option D is wrong because moving to a larger instance increases costs.
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.
✗
Remove Multi-AZ and use a single-AZ deployment to reduce costs.
Why it's wrong here
Removing Multi-AZ sacrifices high availability.
✗
Purchase a Reserved Instance for the current instance type to get a discount.
Why it's wrong here
Reserved Instances lock you into the current over-provisioned instance type.
✓
Change the instance type to a smaller size, such as db.t3.medium, and keep Multi-AZ.
Why this is correct
Downsizing reduces cost while Multi-AZ maintains high availability.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change the instance type to a larger size, such as db.r5.xlarge, to improve performance.
Why it's wrong here
Larger instance increases costs unnecessarily.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which SOA-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.
Cost and Performance Optimization — This question tests Cost and Performance Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change the instance type to a smaller size, such as db.t3.medium, and keep Multi-AZ. — Option C is correct because the instance is over-provisioned; downsizing to a smaller instance type (e.g., db.r5.large to db.t3.medium) reduces cost. Multi-AZ should be retained for high availability. Option A is wrong because removing Multi-AZ sacrifices high availability. Option B is wrong because Reserved Instances require a commitment and may not be cost-effective if the instance type is changed. Option D is wrong because moving to a larger instance increases costs.
What should I do if I get this SOA-C02 question wrong?
Identify which SOA-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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This SOA-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 SOA-C02 exam.
Question Discussion
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