The correct answer is to enable supplemental logging on the source Oracle database manually. This is required because AWS DMS CDC relies on Oracle’s redo logs to capture ongoing changes, and supplemental logging ensures that the necessary before-and-after values for each row modification are recorded. When DMS fails to add this logging automatically—often due to insufficient privileges or database configuration restrictions—the data engineer must execute the command `ALTER DATABASE ADD SUPPLEMENTAL LOG DATA` directly on the source. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of DMS prerequisites for Oracle sources, a common pitfall where candidates mistakenly blame network issues or target compatibility. A frequent trap is assuming DMS can always configure the source automatically, but manual intervention is needed when permissions are limited. Remember the mnemonic: “DMS needs logs, so add supplemental logs” to recall that CDC failures from Oracle almost always point back to missing supplemental logging.
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 DMS to replicate data from an on-premises Oracle database to Amazon RDS for MySQL. The full load completes successfully, but ongoing replication (CDC) is failing with a 'Failed to add supplemental logging' error. What should the data engineer do to resolve this issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable supplemental logging on the source Oracle database manually.
Option B is correct because AWS DMS CDC requires supplemental logging on the source Oracle database to capture changes. The error indicates that DMS cannot enable it automatically, so the engineer must enable it manually. Option A is incorrect because increasing the task log interval does not affect supplemental logging. Option C is incorrect because changing the target engine version is unrelated. Option D is incorrect because the error is not about source connectivity.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Enable supplemental logging on the source Oracle database manually.
Why this is correct
DMS requires supplemental logging for CDC.
Related concept
Standard ACLs match source addresses.
✗
Recreate the DMS endpoint for the source database with a new connection.
Why it's wrong here
Recreating the endpoint does not enable supplemental logging.
✗
Modify the target MySQL database to use a different engine version.
Why it's wrong here
Target engine version is unrelated to source logging.
✗
Increase the task log interval in the DMS task settings.
Why it's wrong here
Log interval does not enable supplemental logging.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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. ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement. 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.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Data Operations and Support — This question tests Data Operations and Support — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Enable supplemental logging on the source Oracle database manually. — Option B is correct because AWS DMS CDC requires supplemental logging on the source Oracle database to capture changes. The error indicates that DMS cannot enable it automatically, so the engineer must enable it manually. Option A is incorrect because increasing the task log interval does not affect supplemental logging. Option C is incorrect because changing the target engine version is unrelated. Option D is incorrect because the error is not about source connectivity.
What should I do if I get this DEA-C01 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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