DBS-C01 Monitoring and Troubleshooting Practice Question
A company is running an Amazon DocumentDB cluster. The application is experiencing high write latency. The cluster has a single instance. What should be done to identify the cause of the latency?
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
✓
Enable Performance Insights and review the top wait events.
Enabling Performance Insights for Amazon DocumentDB allows you to monitor the database load and review top wait events, which helps identify the specific causes of high write latency, such as lock contention or I/O bottlenecks. Option A is wrong because simply upgrading to a larger instance size addresses symptoms but does not identify the root cause. Option C is wrong because adding a replica does not reduce write latency on the primary instance; it only offloads read traffic. Option D is wrong because changing to Provisioned IOPS may improve I/O performance but does not diagnose the underlying issue causing latency.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Upgrade the instance to a larger size.
Why it's wrong here
Scaling without diagnosis may not resolve issue.
- ✓
Enable Performance Insights and review the top wait events.
Why this is correct
Performance Insights reveals database bottlenecks and wait events.
- ✗
Add a replica to distribute the write load.
Why it's wrong here
Replicas do not handle writes in DocumentDB.
- ✗
Change the storage type to Provisioned IOPS.
Why it's wrong here
Storage change may not be the root cause.
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Same concept, more angles
1 more way this is tested on DBS-C01
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Variation 1. A company uses Amazon DocumentDB (with MongoDB compatibility) for its application. The application is experiencing high write latency. The DB cluster has one primary instance and two replicas. Which action should be taken to identify the cause?
hard- A.Migrate the database to Amazon DynamoDB for better write performance.
- B.Add more read replicas to distribute the load.
- ✓ C.Enable Enhanced Monitoring and review OS-level metrics like CPU, memory, and I/O.
- D.Enable slow query logging and analyze slow queries.
Why C: Enabling Enhanced Monitoring at the instance level provides OS-level metrics (CPU, memory, I/O) that can help identify resource bottlenecks causing high write latency on the primary instance. Option A is incorrect because switching to Amazon DynamoDB is a major architectural change, not a troubleshooting step. Option B is incorrect because adding read replicas does not reduce write latency on the primary; replicas handle read traffic, not writes. Option D is incorrect because while slow query logging can identify poorly performing queries, high write latency may also be caused by OS-level resource contention, which Enhanced Monitoring captures.
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.