- A
Use Amazon ElastiCache for Redis to store session data externally.
ElastiCache for Redis is a fast, in-memory store ideal for session management, making the application stateless.
- B
Configure session stickiness on the ALB to route requests from the same user to the same EC2 instance.
Why wrong: Sticky sessions prevent statelessness and can cause uneven load distribution.
- C
Mount an Amazon EFS file system on the EC2 instances and store session files there.
Why wrong: EFS adds complexity and latency; ElastiCache is more suitable for session data.
- D
Store session data in Amazon S3 and update the application to read and write sessions to S3.
Why wrong: S3 is not designed for low-latency, high-frequency session storage; it would introduce significant latency.
Quick Answer
The answer is to use Amazon ElastiCache for Redis as an external session store. By moving session data out of local EC2 instance memory and into a centralized, in-memory data store, the web application becomes stateless, meaning any EC2 instance behind the Application Load Balancer can handle any request without relying on local state. This directly improves availability and scalability because instances can be freely added or removed without session loss. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of decoupling state from compute to achieve horizontal scaling, often appearing as a trap where you must reject sticky sessions (which reintroduce state) or high-latency options like S3. A common memory tip: think of ElastiCache Redis as the “stateless bridge” — it holds the session so your instances don’t have to.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company runs a web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application stores session data locally on the EC2 instances. The company wants to make the application stateless to improve availability and scalability. Which solution should the solutions architect recommend?
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
Use Amazon ElastiCache for Redis to store session data externally.
Option C is correct because ElastiCache with Redis provides a centralized, fast, and durable session store, making the application stateless. Option A is wrong because storing sessions in S3 would introduce high latency and is not designed for high-frequency read/write. Option B is wrong because session stickiness (sticky sessions) on the ALB prevents true statelessness and can cause uneven load. Option D is wrong because mounting an EFS volume for session files still ties sessions to a filesystem but adds complexity and latency compared to ElastiCache.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use Amazon ElastiCache for Redis to store session data externally.
Why this is correct
ElastiCache for Redis is a fast, in-memory store ideal for session management, making the application stateless.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure session stickiness on the ALB to route requests from the same user to the same EC2 instance.
Why it's wrong here
Sticky sessions prevent statelessness and can cause uneven load distribution.
- ✗
Mount an Amazon EFS file system on the EC2 instances and store session files there.
Why it's wrong here
EFS adds complexity and latency; ElastiCache is more suitable for session data.
- ✗
Store session data in Amazon S3 and update the application to read and write sessions to S3.
Why it's wrong here
S3 is not designed for low-latency, high-frequency session storage; it would introduce significant latency.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Continuous Improvement for Existing Solutions — study guide chapter
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FAQ
Questions learners often ask
What does this SAP-C02 question test?
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Amazon ElastiCache for Redis to store session data externally. — Option C is correct because ElastiCache with Redis provides a centralized, fast, and durable session store, making the application stateless. Option A is wrong because storing sessions in S3 would introduce high latency and is not designed for high-frequency read/write. Option B is wrong because session stickiness (sticky sessions) on the ALB prevents true statelessness and can cause uneven load. Option D is wrong because mounting an EFS volume for session files still ties sessions to a filesystem but adds complexity and latency compared to ElastiCache.
What should I do if I get this SAP-C02 question wrong?
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 20, 2026
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.
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