The correct answer is to enable archive log mode on the source Oracle database. AWS DMS requires archive logging to capture ongoing changes for change data capture (CDC) because it reads redo logs to identify inserts, updates, and deletes after the initial full load; without archive logs, DMS cannot access the transaction history needed for continuous replication. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of DMS prerequisites for heterogeneous migrations, often appearing as a trap where candidates mistakenly think a full load alone suffices or that a standby database resolves the issue—neither enables the redo log access DMS needs. Remember the key distinction: full load works without archive logs, but ongoing replication demands them. A simple memory tip is “CDC needs redo, so archive must go”—if you see a DMS CDC failure, always check the source’s archive log mode first.
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. 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 is migrating an on-premises Oracle database to Amazon RDS for Oracle using AWS DMS. The migration fails with an error indicating that DMS cannot capture changes from the source because the archive log mode is not enabled. What should be done?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable archive log mode on the source Oracle database.
Option B is correct because DMS requires archive log mode for ongoing replication. Option A is wrong because DMS can use full load without archive logs, but for ongoing replication it needs them. Option C is wrong because setting up a standby does not help DMS. Option D is wrong because SCT does not affect capture.
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.
✗
Disable ongoing replication and perform a full load only.
Why it's wrong here
While full load works, the company likely needs ongoing replication for minimal downtime.
✗
Set up an Oracle Data Guard standby and use it as the source.
Why it's wrong here
Data Guard does not help with DMS's requirement for archive logs.
✗
Use AWS Schema Conversion Tool (SCT) to convert the schema.
Why it's wrong here
SCT is for schema conversion, not for addressing log mode issues.
✓
Enable archive log mode on the source Oracle database.
Why this is correct
DMS requires archive logging to capture changes for ongoing replication.
Related concept
Standard ACLs match source addresses.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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 DBS-C01 ACL questions on filtering logic and placement.
Deployment and Migration — This question tests Deployment and Migration — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Enable archive log mode on the source Oracle database. — Option B is correct because DMS requires archive log mode for ongoing replication. Option A is wrong because DMS can use full load without archive logs, but for ongoing replication it needs them. Option C is wrong because setting up a standby does not help DMS. Option D is wrong because SCT does not affect capture.
What should I do if I get this DBS-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 DBS-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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