DBS-C01 Workload-Specific Database Design Practice Question
A company needs to store session state for a web application that runs on Amazon EC2 instances behind an Application Load Balancer. The session data is small (less than 1 KB per user) and must be highly available with low latency. Which AWS database service is best for this use case?
⚠ Common exam trap
It's easy for candidates to choose DynamoDB (Option C) because it is a managed NoSQL database with low latency, but they overlook that for sub-millisecond session state, an in-memory cache like Redis is more performant and cost-effective, as DynamoDB's latency is higher and its pricing model is less efficient for very small, high-throughput workloads.
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 ElastiCache for Redis
Amazon ElastiCache for Redis is the best choice because it provides an in-memory data store with sub-millisecond latency, ideal for storing small session state data (less than 1 KB per user). Redis supports key-value operations with built-in data expiration (TTL), making it perfect for session management. Its replication and automatic failover capabilities ensure high availability, meeting the application's requirements.
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 S3
Why it's wrong here
Object storage has high latency for real-time session retrieval.
- ✓
Amazon ElastiCache for Redis
Why this is correct
In-memory storage with low latency and high availability.
- ✗
Amazon DynamoDB
Why it's wrong here
Higher latency for session state compared to Redis.
- ✗
Amazon RDS for MySQL
Why it's wrong here
Relational database adds unnecessary overhead.
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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.