DBS-C01 Deployment and Migration Practice Question
A company is migrating a 500 GB MongoDB database to Amazon DocumentDB. The migration is done using AWS DMS with full load and ongoing replication. The full load completes successfully, but during CDC, the DMS task logs show 'Memory limit exceeded' errors and the task fails repeatedly. The DMS replication instance is a dms.r5.large. The source MongoDB has a write-heavy workload with many small updates. The DBA needs to fix the migration without restarting from scratch. Which action should the DBA take?
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 DMS replication instance size to a larger instance class with more memory.
The 'Memory limit exceeded' error during CDC with a write-heavy workload indicates the replication instance lacks sufficient memory to buffer the changes. Increasing the instance size (e.g., to dms.r5.xlarge) provides more memory. Option B is wrong because reducing BatchApplyEnabled may slow down apply but does not increase memory; it could even worsen the backlog. Option C is wrong because restarting just clears cache temporarily; the error will recur. Option D is wrong because Multi-AZ provides high availability, not additional memory.
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 DMS replication instance size to a larger instance class with more memory.
Why this is correct
More memory allows DMS to buffer more changes and handle the workload.
- ✗
Reduce the DMS task's 'BatchApplyEnabled' setting to apply transactions individually.
Why it's wrong here
This may increase memory usage, not decrease it.
- ✗
Stop and restart the DMS task to clear the cache.
Why it's wrong here
Restarting does not prevent the memory limit from being exceeded again.
- ✗
Enable Multi-AZ on the DMS replication instance to distribute the load.
Why it's wrong here
Multi-AZ is for failover, not for increasing memory capacity.
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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.