DBS-C01 Workload-Specific Database Design Practice Question
A company is designing a database for a real-time bidding system that requires sub-millisecond read and write latency for ad impressions. The workload is heavily write-intensive with occasional reads by campaign IDs. Which AWS database service is most suitable?
⚠ Common exam trap
Many candidates choose ElastiCache for Redis because of its sub-millisecond latency, overlooking that it is not designed as a primary database for write-heavy, durable workloads, and that DynamoDB with DAX provides the same latency with built-in durability and auto-scaling for writes.
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 suitable choice because DynamoDB provides single-digit millisecond latency for read and write operations at any scale, and DAX (DynamoDB Accelerator) is an in-memory cache that reduces read latency to microseconds for frequently accessed items. This combination meets the sub-millisecond read and write latency requirements for a heavily write-intensive real-time bidding system, while supporting occasional reads by campaign IDs via efficient query patterns.
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 DAX
Why this is correct
DynamoDB with DAX provides microsecond to single-digit millisecond latency for high-throughput workloads.
- ✗
Amazon ElastiCache for Redis
Why it's wrong here
ElastiCache is a cache, not a durable database; data loss risk.
- ✗
Amazon DocumentDB
Why it's wrong here
DocumentDB is for document storage and does not provide sub-millisecond latency for heavy writes.
- ✗
Amazon Aurora MySQL
Why it's wrong here
Aurora is relational and cannot guarantee sub-millisecond latency under heavy writes.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.