DBS-C01 Monitoring and Troubleshooting Practice Question
A company is using Amazon ElastiCache for Redis as a caching layer for a web application. Users report that some cached data is missing, causing slower responses. Which ElastiCache feature should be checked first to understand key evictions?
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
✓
Evictions metric in CloudWatch
The Evictions metric in CloudWatch directly shows the number of keys evicted from ElastiCache for Redis due to memory pressure. This is the first metric to check when cached data is missing, as evictions indicate that the cache is full and items are being removed to make space for new ones. Option A (ReplicationLag) measures replication delay between primary and replica nodes, not related to evictions. Option B (CPUUtilization) shows CPU usage but does not indicate evictions. Option D (CacheHits) shows how often requested keys are found in the cache, but does not show evictions. Therefore, option C is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ReplicationLag metric
Why it's wrong here
ReplicationLag indicates how far replica is behind, not evictions.
- ✗
CPUUtilization metric
Why it's wrong here
CPU utilization may correlate with load but not directly evictions.
- ✓
Evictions metric in CloudWatch
Why this is correct
High evictions indicate memory pressure causing key removal.
- ✗
CacheHits metric in CloudWatch
Why it's wrong here
CacheHits shows successful retrievals, not evictions.
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Same concept, more angles
2 more ways this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is using Amazon ElastiCache for Redis as a caching layer for a web application. The application's response time has increased, and the operations team suspects that cache evictions are occurring frequently. Which ElastiCache metric should be monitored to confirm cache evictions?
hard- A.CacheHits
- B.SwapUsage
- ✓ C.Evictions
- D.CurrItems
Why C: The Evictions metric in Amazon ElastiCache for Redis shows the number of keys evicted due to memory pressure. Option A (CacheHits) is wrong because it indicates successful key retrievals, not evictions. Option B (SwapUsage) is wrong because it shows the amount of swap space used, not eviction count. Option D (CurrItems) is wrong because it shows the current number of items in the cache, not evictions.
Variation 2. A company is using Amazon ElastiCache for Redis as a caching layer. The application is experiencing higher latency than expected. The team suspects that cache evictions are occurring due to memory pressure. Which ElastiCache metric should be monitored to confirm this?
medium- A.CurrConnections
- ✓ B.Evictions
- C.ReplicationLag
- D.CacheHits
Why B: The `Evictions` metric in ElastiCache for Redis tracks the number of keys evicted due to memory pressure, which directly indicates cache evictions. Option A is incorrect because `CurrConnections` shows the number of current client connections, not evictions. Option C is incorrect because `ReplicationLag` measures the delay between the primary and replica nodes, not evictions. Option D is incorrect because `CacheHits` shows the number of successful key lookups, not evictions.
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.