DVA-C02 Development with AWS Services Practice Question
A company has a Node.js application running on an EC2 instance. The application needs to store session state. The developer wants to ensure high availability and scalability by storing session data externally. Which AWS service is BEST suited for this purpose?
⚠ Common exam trap
Candidates often choose Amazon DynamoDB because it is a managed key-value store, but they overlook that session state requires ultra-low latency and native TTL support, which Redis provides natively, while DynamoDB's higher latency and eventual consistency can degrade user experience in a high-availability architecture.
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 for external session storage because it provides an in-memory data store with sub-millisecond latency, which is critical for session state access in a high-traffic Node.js application. Redis supports data structures like hashes and TTL (time-to-live) for automatic session expiration, and it can be clustered for high availability and scalability, making it ideal for stateless EC2 instances behind a load balancer.
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
Why it's wrong here
DynamoDB is a good option but typically higher latency than ElastiCache for session data.
- ✗
Amazon S3
Why it's wrong here
S3 is not designed for low-latency session storage.
- ✓
Amazon ElastiCache for Redis
Why this is correct
Redis is commonly used for session caching due to its speed and support for data expiration.
- ✗
Amazon RDS for MySQL
Why it's wrong here
RDS is a relational database and is slower than in-memory solutions for session state.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DVA-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 DVA-C02 exam.