- A
The Aurora cluster was underprovisioned for parallel load
Why wrong: Parallel load improves performance, not causes latency.
- B
Full LOB mode caused large LOBs to be stored in the Aurora cluster, leading to increased I/O
Full LOB mode stores LOBs inline, which can cause write amplification and high latency.
- C
The DMS task was configured with 'ongoing replication' causing continuous write load
Why wrong: Ongoing replication is normal and does not inherently cause high latency.
- D
The DMS task replicated data to a different region, causing network latency
Why wrong: There is no mention of cross-region replication.
Question 1,211 of 1,730
DMS Full LOB Mode Impact
This DBS-C01 practice question tests your understanding of deployment and migration. 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 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 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
✓
Full LOB mode caused large LOBs to be stored in the Aurora cluster, leading to increased I/O
Full LOB mode in AWS DMS loads entire LOBs into memory before writing them to the target, which can cause large LOBs to be stored in the Aurora cluster. This increases I/O and storage overhead, leading to high latency on the Aurora cluster, especially if the LOBs are significantly larger than the default chunk size or if the cluster's I/O capacity is exceeded.
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 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
Read the scenario before looking for a memorised answer.
- ✗
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: answer the scenario, not the keyword
The trap here is that candidates often assume 'full LOB mode' is always safe or that latency must be due to ongoing replication or network issues, but the real cause is the I/O impact of storing large LOBs in Aurora's storage engine.
Detailed technical explanation
How to think about this question
Full LOB mode stores each LOB in its entirety, which can lead to oversized rows or pages in Aurora PostgreSQL, causing write amplification and increased I/O. Aurora's storage layer is optimized for smaller, frequent writes, so large LOBs can trigger excessive page splits and redo log activity, degrading performance. In practice, using limited LOB mode with a maximum LOB size or splitting LOBs into smaller chunks can mitigate this issue.
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.
TExam Day Tips
- 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 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.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DBS-C01 question test?
Deployment and Migration — This question tests Deployment and Migration — Read the scenario before looking for a memorised answer..
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 — Full LOB mode in AWS DMS loads entire LOBs into memory before writing them to the target, which can cause large LOBs to be stored in the Aurora cluster. This increases I/O and storage overhead, leading to high latency on the Aurora cluster, especially if the LOBs are significantly larger than the default chunk size or if the cluster's I/O capacity is exceeded.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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Last reviewed: Jul 4, 2026
This DBS-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 DBS-C01 exam.
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