DBS-C01 Monitoring and Troubleshooting Practice Question
A database specialist is troubleshooting a degraded Amazon Aurora MySQL database cluster. The primary instance is showing elevated read latency and the replica lag is increasing. The DB cluster has one writer and one reader instance. The writer instance is using 90% of its allocated memory, and the reader instance is using 70%. Which action is most likely to reduce read latency and replica lag?
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
✓
Increase the reader instance size to provide more buffer pool memory.
Increasing the reader instance size provides more memory for the buffer pool, which improves read performance and can reduce replica lag. The reader is using 70% memory, so adding more buffer pool memory allows it to cache more data and handle read requests faster. Option A is incorrect because increasing storage improves I/O throughput but does not directly address memory constraints or replica lag. Option B is incorrect because the writer instance is already under memory pressure, but the issue is read latency on the reader, not write performance. Option D is incorrect because adding a second reader distributes the read load but does not resolve the memory bottleneck on the existing reader; a larger instance is more effective in this scenario.
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 allocated storage for the cluster to improve I/O throughput.
Why it's wrong here
Storage size does not affect memory or CPU.
- ✗
Increase the writer instance size to provide more memory for write operations.
Why it's wrong here
Writer memory does not directly affect reader's read latency.
- ✓
Increase the reader instance size to provide more buffer pool memory.
Why this is correct
More memory on the reader allows a larger buffer pool, reducing read latency and helping catch up replication.
- ✗
Add a second reader instance to distribute the read load.
Why it's wrong here
The existing reader is already memory constrained; adding another requires scaling.
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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.