SOA-C02 Monitoring, Logging, and Remediation Practice Question
A SysOps administrator is troubleshooting a slow web application running on EC2 instances behind an ALB. The application uses an RDS MySQL database. The administrator checks CloudWatch metrics and sees that the ALB's latency is high, the RDS CPU is high, and the EC2 CPU is moderate. The application team reports that the database queries are slow. The administrator suspects that the database is the bottleneck. However, the RDS instance is already a db.r5.large and the administrator wants to avoid increasing instance size due to cost. What should the administrator do to improve performance without increasing instance size?
⚠ Common exam trap
Many candidates assume scaling out (more EC2 instances) or adding caching/read replicas will solve a database performance issue, when the real problem is unoptimized queries that need to be identified and fixed first.
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
✓
Enable Performance Insights on the RDS instance to identify slow queries.
Enabling Performance Insights on the RDS instance allows the administrator to identify the specific slow queries causing the bottleneck. This diagnostic tool provides a database load analysis, showing which queries consume the most resources, enabling targeted optimization (e.g., adding indexes or rewriting queries) without increasing instance size. Since the EC2 CPU is moderate and the ALB latency is high due to slow database queries, resolving the query performance directly addresses the root cause.
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 number of EC2 instances to reduce the load on the database.
Why it's wrong here
Scaling out EC2 instances only adds application capacity and increases the pool of concurrent connections to the database. If slow queries are consuming CPU, I/O, or lock resources, more instances will amplify contention and potentially degrade performance further. The underlying issue is likely an inefficient SQL statement or missing index, which must be identified before any capacity changes are considered.
- ✗
Add an ElastiCache Redis cluster to cache database queries.
Why it's wrong here
An ElastiCache Redis cluster can reduce repeated identical read queries, but it does nothing for slow-running queries that miss the cache, for write-heavy workloads, or for queries triggered by unique user parameters. Cache misses still traverse the full query path, and if the slowness stems from resource saturation or suboptimal execution plans, caching masks the symptom without resolving the root cause. Diagnostic analysis of the actual queries is required first.
- ✗
Create a Read Replica and offload read traffic to it.
Why it's wrong here
A Read Replica offloads read-only traffic to a separate endpoint, but asynchronous replication means writes still hit the primary and replicas can lag. If the slow web app is caused by long-running transactions, lock contention, or expensive queries that generate high CPU on the primary, a replica merely distributes the same inefficient workload. It does not improve the performance of the specific queries that are saturating the database.
- ✓
Enable Performance Insights on the RDS instance to identify slow queries.
Why this is correct
RDS Performance Insights provides a real-time and historical dashboard that visualizes database load in terms of wait events and the top SQL statements causing that load. It enables the sysops administrator to identify exactly which queries are slow, whether they suffer from missing indexes, bad execution plans, or resource contention, and then take targeted optimization actions. This is the appropriate first step in troubleshooting a slow database-backed application.
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JA
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.