DBS-C01 Monitoring and Troubleshooting Practice Question
This DBS-C01 practice question tests your understanding of monitoring and troubleshooting. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
Option C is correct because 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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often 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.
Detailed technical explanation
How to think about this question
Under the hood, Aurora MySQL uses asynchronous binlog replication to external MySQL instances, and the 'AuroraBinlogReplicaLag' metric is computed as the difference between the binlog position on the Aurora writer and the position acknowledged by the external replica. In real-world scenarios, a slow network link, an under-provisioned replica, or a large transaction on the Aurora writer can cause this lag to spike, leading to write latency because Aurora may block or throttle writes to prevent binlog files from being purged before they are consumed.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Monitoring and Troubleshooting — This question tests Monitoring and Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The binlog replication to a downstream MySQL instance is falling behind — Option C is correct because 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.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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