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 a 4 TB Oracle database to Amazon Aurora PostgreSQL using AWS DMS. The migration completes successfully but the application experiences high latency on the Aurora cluster. The DMS task used LOB mode 'full LOB mode'. What is the most likely cause of the latency?
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
✓
Full LOB mode caused large LOBs to be stored in the Aurora cluster, leading to increased I/O
Option A is correct because full LOB mode stores LOBs inline, increasing storage and I/O. Option B is wrong because CDC is not the cause. Option C is wrong because DMS does not use cross-region replication. Option D is wrong because parallel load is not the issue.
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.
✗
The Aurora cluster was underprovisioned for parallel load
Why it's wrong here
Parallel load improves performance, not causes latency.
✓
Full LOB mode caused large LOBs to be stored in the Aurora cluster, leading to increased I/O
Why this is correct
Full LOB mode stores LOBs inline, which can cause write amplification and high latency.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
✗
The DMS task was configured with 'ongoing replication' causing continuous write load
Why it's wrong here
Ongoing replication is normal and does not inherently cause high latency.
✗
The DMS task replicated data to a different region, causing network latency
Why it's wrong here
There is no mention of cross-region replication.
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: Full LOB mode caused large LOBs to be stored in the Aurora cluster, leading to increased I/O — Option A is correct because full LOB mode stores LOBs inline, increasing storage and I/O. Option B is wrong because CDC is not the cause. Option C is wrong because DMS does not use cross-region replication. Option D is wrong because parallel load is not the issue.
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.
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?
Standard ACLs match source addresses.
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Question Discussion
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