The answer is Amazon ElastiCache for Redis, because it provides a highly available, low-latency, and scalable external session store that decouples session state from individual EC2 instances. This ensures that if an instance fails or is terminated by an Auto Scaling group, the session data persists and remains accessible to any healthy instance, maintaining application continuity. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of stateless architecture patterns and the pitfalls of ephemeral storage, sticky sessions, or using S3 for low-latency access. A common trap is assuming sticky sessions (session affinity) solve the problem, but they create a single point of failure and prevent even load distribution. Remember the memory tip: “State belongs in a cache, not on a host”—ElastiCache for Redis is purpose-built for this exact use case, offering sub-millisecond performance and replication for high availability.
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 EC2 instances in an Auto Scaling group. The application needs to store session state. The architecture must be highly available and scalable. Which solution should the developer choose?
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 state
Option C is correct because ElastiCache (Redis) provides a highly available, low-latency, and scalable session store that is external to the instances. Option A is wrong because storing session data on the local instance's ephemeral storage is not durable and cannot be shared across instances. Option B is wrong because sticky sessions (session affinity) can cause uneven load and are not highly available if an instance fails. Option D is wrong because storing session data in an S3 bucket would be slow and not designed for low-latency session access.
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 sticky sessions on the Application Load Balancer
Why it's wrong here
Sticky sessions can lead to uneven load and are not highly available.
✗
Store session data in an S3 bucket
Why it's wrong here
S3 is not designed for low-latency session access and would be slow.
✓
Use Amazon ElastiCache for Redis to store session state
Why this is correct
ElastiCache for Redis provides a highly available, scalable, and low-latency session store.
Related concept
Read the scenario before looking for a memorised answer.
✗
Store session data in the instance's ephemeral storage
Why it's wrong here
Ephemeral storage is not durable and cannot be shared across instances.
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 DVA-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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — 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 state — Option C is correct because ElastiCache (Redis) provides a highly available, low-latency, and scalable session store that is external to the instances. Option A is wrong because storing session data on the local instance's ephemeral storage is not durable and cannot be shared across instances. Option B is wrong because sticky sessions (session affinity) can cause uneven load and are not highly available if an instance fails. Option D is wrong because storing session data in an S3 bucket would be slow and not designed for low-latency session access.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-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.
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Question Discussion
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