DBS-C01 Monitoring and Troubleshooting Practice Question
An application uses Amazon ElastiCache for Redis as a session store. Users report that sessions are being lost intermittently. The ElastiCache cluster has replication enabled with one replica. CloudWatch metrics show 'Evictions' spiking during peak hours. 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's memory is full and the eviction policy is removing keys
A spike in 'Evictions' CloudWatch metric indicates that the cache's memory is full, and ElastiCache is evicting keys based on the configured eviction policy (e.g., allkeys-lru). This removal of keys directly causes session data to be lost. Option A is incorrect: replication lag can cause stale reads but not evictions or loss of keys. Option B is incorrect: encryption in transit does not affect memory usage or evictions. Option D is incorrect: automatic snapshots may cause a brief latency spike but do not result in evictions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replication lag between primary and replica is causing read failures
Why it's wrong here
Replication lag would cause stale reads, not session loss.
- ✗
Encryption in transit is enabled and causes decryption errors
Why it's wrong here
Encryption does not cause memory pressure or evictions.
- ✓
The cache's memory is full and the eviction policy is removing keys
Why this is correct
Eviction spikes indicate that the cache is out of memory and is removing keys to make space, causing session loss.
- ✗
The cluster is performing automatic snapshots that block writes
Why it's wrong here
Snapshots may cause brief performance impact but not evictions.
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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.