DBS-C01 Deployment and Migration Practice Question
A company is migrating a 5 TB Oracle database to Amazon Aurora MySQL using AWS DMS. The full load completes successfully, but the CDC phase is slow and the target Aurora cluster is consuming high CPU. The DMS instance type is dms.c4.2xlarge. Which change will most likely improve CDC performance?
⚠ Common exam trap
Many exam-takers assume high CPU on the target means the instance is undersized and needs a larger class (Option D), but the real issue is the DMS apply process being single-threaded, which causes CPU to spike due to inefficient serial writes rather than insufficient compute capacity.
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 number of parallel apply threads in the DMS task
Increasing the number of parallel apply threads in the DMS task allows the CDC phase to apply multiple transactions concurrently to the target Aurora cluster, reducing the backlog of changes. The high CPU on the target suggests the apply process is the bottleneck, not the source or network, and DMS's parallel apply threads directly address this by enabling multi-threaded writes, which improves throughput without requiring larger instances.
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 Aurora cluster's max_connections parameter
Why it's wrong here
This may not directly improve CDC performance.
- ✓
Increase the number of parallel apply threads in the DMS task
Why this is correct
More parallel apply threads can increase the rate of applying changes to Aurora, reducing CPU usage per thread.
- ✗
Increase the DMS task's target storage allocation
Why it's wrong here
DMS does not allocate storage on the target; Aurora manages its own storage.
- ✗
Change the Aurora cluster to a larger instance class
Why it's wrong here
High CPU on target indicates the target is struggling; this could help, but the question asks for DMS change.
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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.