DBS-C01 Multi-AZ deployment Practice Question
A company is running an Amazon RDS for PostgreSQL DB instance with Multi-AZ deployment. They notice that the primary DB instance is experiencing high CPU utilization. The read replica shows normal CPU. Which action should the DBA take to reduce the load on the primary instance?
⚠ Common exam trap
Candidates often confuse Multi-AZ standby with read replicas. The standby is only for high availability and does not serve read traffic, so failing over does not reduce CPU load.
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
✓
Offload SELECT queries to the read replica
Offloading SELECT queries to the read replica reduces CPU utilization on the primary instance because read replicas can handle read traffic independently. Option A is incorrect: failing over to the standby instance does not reduce CPU load—the standby is only for high availability and becomes the new primary, still handling the same workload. Option B is incorrect: increasing the DB instance size would help but is not the best first step; it involves scaling costs and potential downtime, whereas using a read replica is more efficient and cost-effective for read-heavy workloads. Option C is incorrect: converting the read replica to a Multi-AZ standby would make it a synchronous replica for failover, not for offloading reads, so it would not reduce CPU on the primary.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Failover to the standby instance
Why it's wrong here
Failover to the standby instance switches the standby to primary but does not reduce CPU load because the standby was not handling reads; the new primary will still have high CPU.
- ✗
Increase the DB instance size
Why it's wrong here
Increasing the DB instance size would reduce CPU utilization but is more expensive and may cause downtime; it is not the best first step compared to using a read replica.
- ✗
Convert the read replica to a Multi-AZ standby
Why it's wrong here
Converting the read replica to a Multi-AZ standby makes it a synchronous replica for failover, not for reading; it does not offload read traffic and thus does not reduce CPU on the primary.
- ✓
Offload SELECT queries to the read replica
Why this is correct
Offloading SELECT queries to the read replica directly reduces CPU utilization on the primary because read replicas can handle read-only traffic, leaving the primary to process write operations.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 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 DBS-C01 exam.