DBS-C01 Monitoring and Troubleshooting Practice Question
A company is monitoring an Amazon Aurora MySQL DB cluster. They observe that the AuroraReplicaLagMaximum metric is consistently above 10 seconds. Which action would best reduce the 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 instance size of the reader.
Increasing the instance size of the reader can improve its ability to apply changes faster. Option A is wrong because increasing the writer size may not help if the reader is the bottleneck. Option C is wrong because reducing transaction size helps but may not be feasible. Option D is wrong because Multi-AZ is always enabled for Aurora.
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 instance size of the writer.
Why it's wrong here
Incorrect. The writer may not be the bottleneck; the reader might be slow in applying changes.
- ✓
Increase the instance size of the reader.
Why this is correct
Correct. A larger reader instance can apply changes faster, reducing lag.
- ✗
Reduce the number of transactions per second.
Why it's wrong here
Incorrect. This may affect application performance and is not a best practice.
- ✗
Enable Multi-AZ on the cluster.
Why it's wrong here
Incorrect. Aurora clusters are already Multi-AZ.
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Same concept, more angles
1 more way 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 has an Amazon Aurora MySQL DB cluster with one writer and two readers. The application is experiencing high read latency. CloudWatch shows that the 'AuroraBinlogReplicaLag' metric is high for one of the reader instances. What is the most likely cause?
easy- A.The Aurora cluster storage is experiencing high I/O latency
- ✓ B.The reader instance is not keeping up with the write workload from the writer
- C.The reader instance is undersized and needs to be scaled up
- D.The DB cluster parameter group is misconfigured
Why B: The 'AuroraBinlogReplicaLag' metric measures the lag between the writer and a reader when using binary log replication. A high value indicates that the reader is not applying changes from the writer quickly enough, causing read latency. This is typically because the reader instance is not keeping up with the write workload from the writer. Option A is incorrect because Aurora storage is shared and not the cause of replication lag. Option C is incorrect; while an undersized reader can contribute to lag, the primary cause is the reader not keeping pace with writes, not necessarily size. Option D is incorrect because parameter groups affect settings but not replication lag directly.
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.