DBS-C01 Monitoring and Troubleshooting Practice Question
A database engineer is troubleshooting a production Amazon Aurora MySQL DB cluster. The application is experiencing high latency on write operations. The engineer checks the Amazon CloudWatch metrics and sees that the 'AuroraBinlogReplicaLag' metric is high. What is the most likely cause of the write latency?
⚠ Common exam trap
It's easy for candidates to confuse 'AuroraBinlogReplicaLag' with Aurora's internal replication lag (e.g., ReplicaLag for Aurora Replicas) or with general performance metrics like CPU or storage, leading them to select incorrect options that do not address the specific binlog replication context.
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 binlog replication to a downstream MySQL instance is falling behind
The 'AuroraBinlogReplicaLag' metric specifically measures the lag between the Aurora MySQL cluster and an external MySQL instance that is replicating from Aurora using binary log (binlog) replication. When this lag is high, it indicates that the downstream MySQL instance is falling behind in applying binlog events, which can cause write operations on the Aurora cluster to stall or slow down due to the synchronous nature of binlog generation and the need to retain binlogs until they are consumed by the replica.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The DB cluster has insufficient storage capacity for the binlog files
Why it's wrong here
Insufficient storage would cause errors, not binlog lag.
- ✗
The DB cluster has a high CPU utilization that is causing replication lag
Why it's wrong here
CPU utilization is a separate metric; binlog lag is specific to replication.
- ✓
The binlog replication to a downstream MySQL instance is falling behind
Why this is correct
High binlog lag means the downstream replica cannot keep up, causing write delays if the source waits for acknowledgment.
- ✗
A recent failover event caused the binlog to be replayed from the last checkpoint
Why it's wrong here
Failover does not cause binlog lag; it may cause a brief stall but not sustained high lag.
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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.