- A
Increase the session timeout in the application configuration.
Why wrong: This would not reduce memory usage; it might increase it.
- B
Enable the 'allkeys-lru' eviction policy in the Redis parameter group.
Eviction policies allow Redis to free memory by removing keys when limit is reached.
- C
Reduce the number of EC2 instances behind the load balancer.
Why wrong: This does not address Redis memory usage.
- D
Migrate from Redis to a Memcached cluster.
Why wrong: Memcached also has memory limits; migration is not a direct solution.
Question 966 of 1,616
Configuring Redis Eviction Policy for Session Storage
This DVA-C02 practice question tests your understanding of development with aws services. 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 behind an Application Load Balancer. The application uses sessions stored in an ElastiCache Redis cluster. Recently, users have been experiencing session timeouts and errors. The developer notices that the Redis cluster is running out of memory. What should the developer do to resolve this issue?
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
✓
Enable the 'allkeys-lru' eviction policy in the Redis parameter group.
The correct answer is B because enabling the 'allkeys-lru' eviction policy in the Redis parameter group allows Redis to automatically evict the least recently used keys when memory is full, preventing session timeouts and errors caused by out-of-memory conditions. This policy is specifically designed for use cases like session storage where losing old sessions is acceptable to free memory for new ones.
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.
- ✗
Increase the session timeout in the application configuration.
Why it's wrong here
This would not reduce memory usage; it might increase it.
- ✓
Enable the 'allkeys-lru' eviction policy in the Redis parameter group.
Why this is correct
Eviction policies allow Redis to free memory by removing keys when limit is reached.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Reduce the number of EC2 instances behind the load balancer.
Why it's wrong here
This does not address Redis memory usage.
- ✗
Migrate from Redis to a Memcached cluster.
Why it's wrong here
Memcached also has memory limits; migration is not a direct solution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse eviction policies with TTL-based expiration, thinking that increasing session timeouts (Option A) or reducing application instances (Option C) will solve memory pressure, when in fact only a proper eviction policy directly addresses out-of-memory errors in Redis.
Detailed technical explanation
How to think about this question
Redis eviction policies are configured via the 'maxmemory-policy' parameter in the parameter group; 'allkeys-lru' applies the LRU algorithm to all keys regardless of TTL, making it ideal for session stores where sessions have no explicit expiration. Under the hood, Redis uses an approximation of LRU (not true LRU) to reduce memory overhead, sampling a subset of keys to evict. In a real-world scenario, if the application sets session TTLs but they are too long, 'allkeys-lru' ensures that the cluster remains operational under load spikes without manual intervention.
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.
TExam Day Tips
- 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.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable the 'allkeys-lru' eviction policy in the Redis parameter group. — The correct answer is B because enabling the 'allkeys-lru' eviction policy in the Redis parameter group allows Redis to automatically evict the least recently used keys when memory is full, preventing session timeouts and errors caused by out-of-memory conditions. This policy is specifically designed for use cases like session storage where losing old sessions is acceptable to free memory for new ones.
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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.
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