DBS-C01 Workload-Specific Database Design Practice Question
A company is building a real-time chat application that requires storing messages with a maximum of 10,000 characters per message. The application needs sub-millisecond latency for reads and writes. The data must be durable and replicated across three Availability Zones. The development team wants to minimize operational overhead. Which AWS database service is most appropriate?
⚠ Common exam trap
Many candidates choose ElastiCache for Redis (Option A) because of its sub-millisecond latency, overlooking the requirement for durable, multi-AZ replicated storage that Redis alone does not provide natively without additional configuration and operational overhead.
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 DAX
Amazon DynamoDB with DAX is the most appropriate choice because it provides single-digit millisecond latency for reads and writes, supports up to 400 KB per item (easily accommodating 10,000 characters), and offers built-in replication across three Availability Zones for durability. DAX (DynamoDB Accelerator) further reduces read latency to sub-millisecond by serving as an in-memory cache, while DynamoDB itself handles write durability and replication automatically, minimizing operational overhead.
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 ElastiCache for Redis with replication
Why it's wrong here
Not durable; data loss on failure.
- ✓
Amazon DynamoDB with DAX
Why this is correct
Serverless, sub-millisecond latency, durable, multi-AZ.
- ✗
Amazon RDS for PostgreSQL with Multi-AZ
Why it's wrong here
Operational overhead and higher latency.
- ✗
Amazon Aurora MySQL with Multi-AZ
Why it's wrong here
May not provide sub-millisecond latency for writes.
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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.