SAP-C02 Continuous Improvement for Existing Solutions Practice Question
A company operates a web application on Amazon EC2 instances behind an Application Load Balancer. The application stores session state in a self-managed Redis cluster on EC2. During a recent marketing campaign, the Redis cluster became a bottleneck, causing session timeouts and poor user experience. The company wants to improve the solution's scalability and resilience with minimal operational overhead. Which solution should a solutions architect recommend?
⚠ Common exam trap
The trap here is assuming that any managed database service will automatically reduce operational overhead without considering application compatibility and specific workload characteristics.
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
✓
Migrate the session store to Amazon ElastiCache for Redis with cluster mode enabled and automatic failover.
Migrating to Amazon ElastiCache for Redis with cluster mode enabled provides a managed, scalable, and highly available session store. It eliminates the operational burden of self-managed Redis while offering automatic sharding and failover. This directly resolves the bottleneck and improves resilience. Other options either require significant application changes, introduce latency, or do not address scalability.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replace the self-managed Redis cluster with an Amazon DynamoDB table using on-demand capacity mode and DAX.
Why it's wrong here
While DynamoDB with DAX offers scalability and low latency, it requires significant application changes to replace Redis session storage. The scenario emphasizes minimal operational overhead, but migrating to a different data model and API introduces development effort and risk. Additionally, DAX is designed for read-heavy workloads, not session state writes, making it less suitable for this use case.
- ✓
Migrate the session store to Amazon ElastiCache for Redis with cluster mode enabled and automatic failover.
Why this is correct
ElastiCache for Redis with cluster mode enabled provides horizontal scaling, automatic sharding, and failover, directly addressing the bottleneck and resilience needs. It is a fully managed service, reducing operational overhead compared to self-managed Redis on EC2. The application can continue using the Redis protocol with minimal code changes, and the solution scales read/write capacity as demand grows.
- ✗
Configure the EC2 instances to store session state in Amazon S3 with Transfer Acceleration enabled.
Why it's wrong here
Amazon S3 is not designed for low-latency, high-frequency session state access. Using S3 as a session store would introduce significant latency and potential consistency issues, especially under high concurrency. Transfer Acceleration optimizes uploads over long distances but does not make S3 suitable for session management, and it adds complexity without solving the bottleneck.
- ✗
Enable sticky sessions on the Application Load Balancer and store session state in instance memory.
Why it's wrong here
Sticky sessions with in-memory storage do not improve scalability or resilience; they tie users to specific instances, causing uneven load and session loss if an instance fails. This approach increases operational overhead and does not address the Redis bottleneck. It also prevents horizontal scaling benefits and can lead to poor user experience during instance replacements or scaling events.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SAP-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 SAP-C02 exam.