The answer is a large full load being transferred, which delays the start of CDC. When AWS DMS performs a full load of existing data before beginning change data capture, the replication instance must complete that initial transfer before it can start reading and applying ongoing changes from the source PostgreSQL transaction logs. If the full load is massive, the target can fall behind by hours because CDC simply hasn't started yet. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of the DMS lifecycle phases—full load, then CDC—and the common misconception that CDC lag always means a performance bottleneck in the replication engine. A frequent trap is assuming you need a larger instance or parallel apply, but those only help after CDC is active. Memory tip: think "Full Load First, CDC Later"—if the target is lagging before CDC begins, the full load is the culprit.
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company uses AWS Database Migration Service (DMS) to migrate an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The migration is ongoing and uses change data capture (CDC). The engineer notices that the target database is falling behind the source by several hours. What is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A large full load is being transferred, which delays the start of CDC.
Option B is correct because a large full load can delay the start of CDC, causing the target to fall behind. Option A is incorrect because increasing the replication instance size typically improves performance. Option C is wrong because CDC requires an active transaction log; disabling it would stop replication. Option D is wrong because parallel apply can actually speed up replication.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 target table has disabled parallel apply.
Why it's wrong here
Disabling parallel apply may slow down but not typically cause hours of lag.
✓
A large full load is being transferred, which delays the start of CDC.
Why this is correct
Full load must complete before CDC begins, causing a backlog.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The replication instance is under-provisioned and needs to be larger.
Why it's wrong here
Under-provisioning may cause slowness but the question asks for most likely cause.
✗
Change data capture has been disabled on the source database.
Why it's wrong here
If CDC were disabled, no changes would be captured at all.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A large full load is being transferred, which delays the start of CDC. — Option B is correct because a large full load can delay the start of CDC, causing the target to fall behind. Option A is incorrect because increasing the replication instance size typically improves performance. Option C is wrong because CDC requires an active transaction log; disabling it would stop replication. Option D is wrong because parallel apply can actually speed up replication.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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