DBS-C01 Monitoring and Troubleshooting Practice Question
A startup uses Amazon ElastiCache for Redis as a caching layer for its database. Users report that application responses are slow. The developer checks the ElastiCache metrics and sees that 'CacheHits' are low and 'CacheMisses' are high. What is the most likely cause?
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
✓
The cache key TTL is too short, causing frequent evictions.
A low cache hit ratio and high cache miss ratio indicate that the cache is not storing data that is frequently requested. The most likely cause is that the Time-To-Live (TTL) for cache keys is set too short, causing data to be evicted before it can be reused. Option A is incorrect because read replicas improve read scalability but do not directly affect cache hit ratio. Option B is incorrect because write capacity is not relevant for a caching layer that primarily serves reads. Option C is incorrect: while high CPU utilization can cause latency, it would not specifically cause low cache hits and high misses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The cluster does not have enough read replicas.
Why it's wrong here
Read replicas help with read scaling, but do not affect cache hit ratio.
- ✗
The ElastiCache cluster does not have enough write capacity.
Why it's wrong here
ElastiCache is in-memory; write capacity is not a relevant metric.
- ✗
The ElastiCache nodes have high CPU utilization.
Why it's wrong here
High CPU may slow responses but does not directly cause low cache hits.
- ✓
The cache key TTL is too short, causing frequent evictions.
Why this is correct
Short TTL leads to early eviction and cache misses.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 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 DBS-C01 exam.