SOA-C02 Cost and Performance Optimization Practice Question
An application runs on EC2 instances behind an ALB. Users report slow response times. CPU utilization averages 90% during peak hours. What is the MOST effective way to improve performance?
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
✓
Increase the instance size to a larger type.
Increasing the instance size (scaling up) provides more CPU resources directly, addressing the high utilization. While Auto Scaling could add more instances, the question specifically asks about the given options, and D is the most effective among them. Detailed monitoring (A) only provides metrics, not performance improvement. Memory-optimized (B) does not help CPU-bound issues. Security group rules (C) do not affect compute performance.
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 detailed monitoring on CloudWatch.
Why it's wrong here
Enable detailed monitoring on CloudWatch only increases the frequency of metric collection from 5 minutes to 1 minute, which incurs additional charges without altering the instance's compute capacity. It provides more granular visibility into CPU utilization, but does not reduce the actual CPU load caused by the ALB traffic, so it cannot resolve the underlying performance issue.
- ✗
Switch to a memory-optimized instance type.
Why it's wrong here
Switching to a memory-optimized instance type, such as the R family, increases the RAM-to-vCPU ratio but does not necessarily provide more CPU throughput. Since the application is experiencing high CPU utilization and the bottleneck is compute capacity rather than memory pressure, changing to a memory-intensive instance would leave the CPU saturation unaddressed and is not an effective fix.
- ✗
Add more Security Group rules.
Why it's wrong here
Security Group rules function as a stateful virtual firewall at the network interface level, and adding rules does not affect instance CPU capacity or performance. The ALB is already successfully forwarding requests, so the issue is not blocked traffic or inadequate filtering; additional rules would only increase administrative complexity and could not reduce high CPU utilization.
- ✓
Increase the instance size to a larger type.
Why this is correct
Increasing the instance size to a larger type in the same family directly adds vCPUs and baseline CPU capacity, which helps absorb the workload being distributed by the ALB. For example, moving from one size to the next doubles the number of vCPUs and often increases network bandwidth, allowing the instance to process more concurrent requests without saturating the CPU. This vertical scaling approach correctly addresses the stated CPU-bound bottleneck.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.