SAA-C03 Design High-Performing Architectures Practice Question
A retail company runs a read-heavy product catalog on Amazon RDS for MySQL. During flash sales, read replicas lag behind the primary and the application serves stale prices. The team wants to scale read traffic while ensuring the application reads the most current data for price lookups. Which solution should a solutions architect recommend?
⚠ Common exam trap
The trap here is assuming that scaling read replicas also guarantees fresh data, when asynchronous replication means replicas can lag regardless of their size.
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
✓
Route price lookups to the primary DB instance and other reads to read replicas.
RDS read replicas use asynchronous replication, so they can lag under write-heavy flash-sale conditions. Price lookups need the latest committed value, so sending them to the primary guarantees freshness, while other reads continue to use replicas for scale. Multi-AZ standbys cannot serve reads, and simply adding replica capacity does not eliminate lag, so routing consistency-sensitive queries to the primary is the correct design.
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 Multi-AZ on the RDS for MySQL instance and point all reads to the standby.
Why it's wrong here
A Multi-AZ standby exists for failover and does not serve read traffic. It cannot be used to scale reads, and pointing the application at the standby is not a supported pattern. This option neither increases read throughput nor guarantees fresh reads, so it fails both parts of the requirement.
- ✗
Increase the size of the read replicas and enable automatic scaling of replicas.
Why it's wrong here
Larger or additional read replicas improve throughput but do not reduce replication lag to zero. Price lookups would still risk reading stale data during flash sales. Scaling replicas addresses capacity, not consistency, so it does not satisfy the requirement to serve the most current price data.
- ✗
Configure the application to retry reads on a replica until the price matches the primary.
Why it's wrong here
Comparing replica and primary values on every read doubles query load and adds latency, and it is not a reliable consistency mechanism. It also requires application logic changes and can still return stale data under load. This is an anti-pattern compared with routing consistency-sensitive reads to the primary.
- ✓
Route price lookups to the primary DB instance and other reads to read replicas.
Why this is correct
Read replicas are asynchronous, so they can lag during heavy write periods. Directing price lookups, which require the latest committed data, to the primary instance guarantees current values, while offloading less sensitive reads to replicas preserves read scaling. This matches the requirement for fresh prices without abandoning replica-based scaling.
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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 SAA-C03 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 SAA-C03 exam.