DEA-C01 Data Operations and Support Practice Question
A company uses AWS Database Migration Service (DMS) to migrate an on-premises Oracle database to Amazon RDS for PostgreSQL. The migration completes successfully, but the data engineer notices that some tables have fewer rows in the target than the source. Which DMS setting should be checked to ensure full data migration?
⚠ Common exam trap
Many candidates assume row count mismatches are always due to LOB settings or validation being off, but the most direct cause is data type conversion errors logged in the task logs, which DMS does not surface in the task status summary.
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 task logs show that some rows failed to apply due to data type conversion errors.
If some rows failed to apply due to data type conversion errors, those rows would be logged as errors and not written to the target, resulting in fewer rows. AWS DMS task logs capture these failures, and checking them is the direct way to identify rows that were skipped or rejected during migration. This is the most common cause of row count mismatches after a successful DMS task.
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 LOB mode is set to 'Limited LOB mode' instead of 'Full LOB mode'.
Why it's wrong here
LOB mode affects how large objects are handled, not regular rows.
- ✓
The task logs show that some rows failed to apply due to data type conversion errors.
Why this is correct
Failed rows would be logged and can be reviewed.
- ✗
The 'Enable validation' option is turned off.
Why it's wrong here
Validation checks data after migration, does not affect migration completeness.
- ✗
The 'Parallel Apply' feature is disabled, slowing down the migration.
Why it's wrong here
Speed, not completeness.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-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 DEA-C01 exam.