The answer is to scale up to a larger DB instance class. This is correct because when high CPU utilization persists despite query optimization and connection pooling, the bottleneck is the instance’s raw compute capacity; vertical scaling directly increases vCPUs and memory, providing more processing power to handle the sustained load without adding architectural complexity. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of when to choose vertical scaling over horizontal scaling with read replicas—a common trap is assuming read replicas solve CPU issues, but they only offload read traffic, not compute-bound processing. Remember the memory tip: “CPU high? Scale up, not out—read replicas handle reads, not compute.”
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 is running a production Amazon RDS for MySQL database that is experiencing performance degradation. Amazon CloudWatch metrics show high CPU utilization and high number of connections. The company has already optimized queries and implemented connection pooling. What is the MOST cost-effective solution to address the high CPU utilization?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Scale up to a larger DB instance class
Option D is correct because scaling up to a larger DB instance class directly increases the compute capacity (vCPUs and memory) available to the database, which addresses the root cause of high CPU utilization. Since queries are already optimized and connection pooling is in place, the remaining bottleneck is the instance's processing power, making a vertical scale-up the most cost-effective solution to handle the sustained CPU load without introducing additional architectural complexity.
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.
✗
Add Read Replicas to offload read traffic
Why it's wrong here
Read Replicas offload reads, but CPU on primary may still be high if writes are the issue.
✗
Change the storage type to Provisioned IOPS (io1)
Why it's wrong here
Provisioned IOPS improves I/O, not CPU.
✗
Enable RDS Proxy to reduce database connections
Why it's wrong here
Connection pooling is already implemented; RDS Proxy further reduces overhead but not CPU.
✓
Scale up to a larger DB instance class
Why this is correct
More CPU capacity directly addresses high CPU utilization.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose RDS Proxy (Option C) assuming it reduces CPU utilization by lowering connection overhead, but the question explicitly states connection pooling is already implemented, so the CPU issue is from compute-bound operations, not connection management.
Detailed technical explanation
How to think about this question
RDS instance classes are backed by specific EC2 instance types with dedicated CPU cores and memory; scaling up (e.g., from db.r5.large to db.r5.xlarge) doubles the vCPU count, allowing the database engine to handle more concurrent query execution and reduce CPU saturation. In MySQL, high CPU usage often stems from inefficient query execution plans or contention, but when query optimization is exhausted, vertical scaling provides immediate relief without requiring application changes or additional read replicas. The cost-effectiveness comes from avoiding the overhead of managing replicas or proxy layers when the primary bottleneck is compute capacity.
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.
TExam Day Tips
→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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Scale up to a larger DB instance class — Option D is correct because scaling up to a larger DB instance class directly increases the compute capacity (vCPUs and memory) available to the database, which addresses the root cause of high CPU utilization. Since queries are already optimized and connection pooling is in place, the remaining bottleneck is the instance's processing power, making a vertical scale-up the most cost-effective solution to handle the sustained CPU load without introducing additional architectural complexity.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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