DBS-C01 Management and Operations Practice Question
A financial services company runs an Amazon Aurora MySQL database cluster with a single writer and two readers. The cluster handles critical transactional workloads. Over the past month, the database experienced intermittent read replica lag spikes that caused stale reads in application queries. The database administrator needs to identify the root cause and reduce replica lag. Which THREE steps should the administrator take to diagnose and mitigate the 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
✓
Use Performance Insights on the reader instances to identify high-load queries causing resource contention.
Using Performance Insights on reader instances helps identify high-load queries causing resource contention, which can lead to replica lag. Option D is correct because a high binlog retention hours parameter can cause the replica to spend more time replaying binary logs; reducing it can mitigate lag. Option E is correct because enabling slow query logging on the writer instance helps identify long-running transactions that may lock rows or generate excessive binlog data, thereby causing replication delays. Option A is incorrect because switching from an Aurora cluster to a Multi-AZ DB instance does not address replica lag; Multi-AZ is for failover redundancy, not replication performance. Option B is incorrect because upgrading reader instances to match the writer's class may help if readers are underpowered, but this is not a direct diagnostic step and may not resolve the root cause if the issue stems from the writer side.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Switch from a single-writer cluster to Multi-AZ DB instance to reduce replication lag.
Why it's wrong here
Multi-AZ is for high availability, not for reducing replica lag.
- ✗
Upgrade the reader instances to a larger instance class to match the writer.
Why it's wrong here
Reader instance size may not be the cause; lag often originates from writer workload.
- ✓
Use Performance Insights on the reader instances to identify high-load queries causing resource contention.
Why this is correct
Performance Insights can pinpoint resource bottlenecks on readers.
- ✓
Check the binlog retention hours parameter and reduce it if set to a high value.
Why this is correct
High binlog retention can increase replication lag; reducing it may help.
- ✓
Enable slow query logging on the writer instance and analyze long-running transactions.
Why this is correct
Long-running transactions on the writer can delay replication to readers.
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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.