DEA-C01 Data Operations and Support Practice Question
A company runs a critical PostgreSQL database on Amazon RDS. The database experiences high read latency during peak hours. The data engineer needs to reduce read latency with minimal changes to the application. Which solution is MOST effective?
⚠ Common exam trap
DEA-C01 often tests the misconception that Multi-AZ or scaling up the primary instance improves read performance, when in fact only read replicas provide read scaling with minimal application changes.
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
✓
Create a read replica of the RDS instance and redirect read queries to it.
A read replica is a separate RDS instance that receives asynchronous replication from the primary. By redirecting read-only queries to the replica, you offload read traffic from the primary, directly reducing read latency during peak hours. This requires minimal application changes—typically just updating the connection string for read operations. Multi-AZ and larger instance classes do not provide a dedicated read-scaling endpoint, and deleting indexes would harm 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.
- ✗
Delete unused indexes to improve query performance.
Why it's wrong here
Dropping unused indexes frees write overhead and storage but does not add read capacity, so peak-hour read latency persists. It is tempting because index tuning often helps queries, yet it is correct when indexes are redundant and slowing inserts, not when read throughput is the bottleneck.
- ✗
Enable Multi-AZ deployment for automatic failover.
Why it's wrong here
Multi-AZ maintains a synchronous standby for failover; the standby does not serve reads, so peak read latency is unchanged. It is tempting as a resilience feature, but it is correct when the requirement is high availability across an Availability Zone outage, not read scaling.
- ✗
Increase the DB instance class to a larger size with more memory.
Why it's wrong here
Scaling the instance class adds CPU and memory, but read latency stems from repeated query execution against the primary; it does not offload reads. It is tempting because vertical scaling helps CPU-bound or memory-constrained workloads, yet the scenario needs read replicas or caching to serve read traffic separately.
- ✓
Create a read replica of the RDS instance and redirect read queries to it.
Why this is correct
Read replicas offload read traffic to a separate RDS instance via PostgreSQL's asynchronous streaming replication, directly reducing contention on the primary and cutting read latency. Redirecting read queries requires only connection-string changes, satisfying the stem's minimal-application-change constraint. Unlike Multi-AZ standby, replicas serve reads.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This DEA-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 DEA-C01 exam.