SAA-C03 Design Resilient Architectures Practice Question
A logistics company runs an order-tracking service that exposes a REST API. The service must remain available during a single Availability Zone failure and must keep read latency low for a globally distributed user base. The data store must support automatic multi-AZ replication without the team managing database servers. Which solution meets these requirements?
⚠ Common exam trap
The trap here is choosing an RDS read replica for failover, when read replicas are not automatic failover targets and require manual promotion.
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 DynamoDB with global tables and on-demand capacity mode.
DynamoDB is a fully managed, multi-AZ key-value store, so a single Availability Zone failure does not interrupt service and no database servers are managed. Global tables replicate data across Regions so users read from a nearby replica with low latency, and on-demand capacity removes the need to provision throughput, meeting both resilience and performance goals.
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 DynamoDB with global tables and on-demand capacity mode.
Why this is correct
DynamoDB is a fully managed, multi-AZ service by default, and global tables replicate data across Regions for low-latency reads near users. On-demand capacity removes provisioning concerns. The team does not manage servers, and the design remains available during a single Availability Zone failure without manual failover steps.
- ✗
Amazon RDS for MySQL with a read replica in a second Availability Zone.
Why it's wrong here
A read replica is asynchronous and is not an automatic failover target for the primary, so a zonal failure of the primary requires manual promotion. The team would also manage the database engine and instance patching. This does not meet the requirement for automatic multi-AZ replication without server management.
- ✗
Amazon ElastiCache for Redis with a cluster mode disabled replication group in one Availability Zone.
Why it's wrong here
A single-AZ replication group fails if that Availability Zone is lost, and ElastiCache is an in-memory cache rather than a durable system of record for orders. It does not provide multi-AZ durability for the tracking data and would not satisfy the availability requirement without additional persistence.
- ✗
Amazon RDS for PostgreSQL with Multi-AZ DB instance deployment and a cross-Region read replica.
Why it's wrong here
Multi-AZ RDS provides automatic failover, but the team still manages the database engine and instance classes, and a cross-Region read replica adds cost and complexity without improving single-AZ resilience. It does not match the fully managed, serverless operational model that DynamoDB offers.
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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 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.