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DEA-C01 Data Operations and Support Practice Question

A company uses AWS DMS to migrate a 2 TB Oracle database to Amazon RDS for PostgreSQL. The migration completes successfully, but data validation shows some tables have missing rows. The task is configured for ongoing replication using change data capture (CDC). What is the MOST likely cause of the missing rows?

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

✓

Source tables missing primary keys

If a table lacks a primary key, DMS cannot uniquely identify rows for CDC, leading to missed changes. Option A is wrong because the endpoint connection is valid (migration completed). Option B is wrong because CDC captures changes from redo logs, not the source database directly. Option D is wrong because DMS supports large objects with proper configuration.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✗

    Source database archive log retention period too short

    Why it's wrong here

    Short retention might cause CDC gaps, but missing rows in full load validation suggest initial load issues.

  • ✗

    Large objects (LOBs) not supported by the target

    Why it's wrong here

    DMS supports LOBs; this would cause errors, not silent missing rows.

  • ✓

    Source tables missing primary keys

    Why this is correct

    Without primary keys, DMS cannot track changes for CDC, leading to missing rows.

  • ✗

    Insufficient storage on the DMS replication instance

    Why it's wrong here

    Storage issues would cause task failure, not missing rows with a successful migration.

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JA

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.