Read-Heavy Relational Database with RDS Read Replicas
A company is designing a new application that requires a relational database with high read capacity. The application is read-heavy and requires low latency. Which database configuration should be used?
Quick Answer
The answer is Amazon RDS with read replicas. This configuration is correct because a read-heavy relational database with low latency requires offloading read traffic from the primary instance to multiple read replicas, which scale read capacity horizontally and reduce latency by distributing the load across synchronized copies of the data. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of when to scale reads versus writes—a common trap is choosing Amazon DynamoDB DAX or ElastiCache, but the question explicitly requires a relational database, so RDS read replicas are the only fit. A key memory tip: if the workload is read-heavy and relational, think "replicas for reads, Aurora for auto-scaling."
⚠ Common exam trap
Test-takers frequently confuse Multi-AZ deployments with read replicas, assuming Multi-AZ also improves read performance, but Multi-AZ only provides failover redundancy and does not offload read traffic.
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
✓
Amazon RDS with read replicas
Amazon RDS with read replicas is the correct choice because the application is read-heavy and requires low latency. Read replicas offload read traffic from the primary database instance, scaling read capacity and reducing latency for read operations by distributing the load across multiple copies of the data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Amazon RDS with read replicas
Why this is correct
Read replicas offload read queries from the primary instance via asynchronous replication, directly satisfying the read-heavy, low-latency requirement. They scale read capacity horizontally across multiple replicas, unlike a single Multi-AZ standby which serves no read traffic.
- ✗
Amazon DynamoDB with DAX
Why it's wrong here
DynamoDB is a NoSQL key-value store, so it cannot satisfy the stem's relational requirement regardless of DAX caching. DAX accelerates reads for DynamoDB tables, which is tempting because the scenario stresses read-heavy, low-latency access. It would be correct if the workload needed a non-relational store at massive scale.
- ✗
Amazon RDS with Multi-AZ deployment
Why it's wrong here
Amazon RDS Multi-AZ maintains a synchronous standby in a second Availability Zone purely for failover, so it does not add read capacity — the standby is inaccessible to your application. It is tempting because Multi-AZ genuinely delivers high availability and automatic failover, making it the right pick when resilience, not read scaling, is the stated requirement.
- ✗
Amazon ElastiCache for Redis
Why it's wrong here
Amazon ElastiCache for Redis is an in-memory cache, not a relational database, so it cannot satisfy the stem's requirement for a relational engine with persistent SQL storage. It is tempting because it delivers the low-latency read throughput the scenario demands, and would be the right choice for caching query results alongside a relational database.
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Same concept, more angles
1 more way this is tested on SAP-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is designing a new application that requires a relational database with automated backups and multi-AZ redundancy. The database workload is predictable with occasional read replicas for reporting. Which AWS service should be used?
medium- ✓ A.Amazon RDS
- B.Amazon Redshift
- C.Amazon DynamoDB
- D.Amazon ElastiCache
Why A: Amazon RDS is the correct choice because it provides managed relational databases (e.g., MySQL, PostgreSQL, Oracle, SQL Server) with built-in automated backups and Multi-AZ redundancy for high availability. The workload is predictable and requires occasional read replicas for reporting, both of which are natively supported by RDS without the need for complex configuration.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-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 SAP-C02 exam.