DVA-C02 Development with AWS Services Practice Question
A developer wants to store session state for a web application that runs on multiple EC2 instances behind an Application Load Balancer. Which AWS service should the developer use to store the session state in a centralized, highly available location?
⚠ Common exam trap
The trap here is that candidates mistakenly choose Amazon RDS for session storage due to its familiarity with databases, overlooking that session state is transient and requires low-latency access, which ElastiCache's in-memory architecture provides far more efficiently.
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
Amazon ElastiCache is the correct choice because it provides a managed, in-memory caching service that supports Redis or Memcached, which are ideal for storing session state in a centralized, highly available manner. Session data requires low-latency reads and writes, and ElastiCache offers sub-millisecond performance, replication across multiple Availability Zones, and automatic failover, making it suitable for stateless web applications behind an Application 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 RDS
Why it's wrong here
Amazon RDS is a managed relational database service, optimized for structured data storage requiring transactional integrity and complex querying. While it could store session data, its disk-based nature and the overhead of maintaining ACID properties make it inefficient and costly for high-volume, low-latency key-value lookups typical of session state. The frequent small reads and writes would incur significant I/O operations and latency, impacting web application performance.
- ✗
Amazon S3
Why it's wrong here
Amazon S3 is an object storage service designed for durability and scalability of large, static files or objects, not for dynamic, frequently updated, small key-value pairs. Each session state update would involve a full object overwrite, incurring high latency and API call costs, which is unsuitable for the rapid read/write patterns required by session management. Its eventual consistency model can also lead to stale session data, further compromising user experience.
- ✓
Amazon ElastiCache
Why this is correct
Amazon ElastiCache is a fully managed in-memory caching service, offering high-performance, low-latency data retrieval using Redis or Memcached engines. It is specifically designed for use cases like session state management, where rapid access to frequently changing, ephemeral key-value data is critical. Its in-memory nature significantly reduces I/O latency compared to disk-based solutions, ensuring a responsive user experience and easily scaling to handle high request volumes.
- ✗
AWS Lambda
Why it's wrong here
AWS Lambda is a serverless compute service that executes code in response to events, providing a highly scalable and ephemeral execution environment. It is fundamentally a compute service, not a persistent storage solution for application data like session state. While Lambda functions can interact with storage services, they do not inherently store data between invocations, making them unsuitable for maintaining user session information directly.
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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.