The answer is to use a larger DMS replication instance, such as dms.c5.large instead of dms.t3.medium, because a larger instance provides more CPU and memory to process the change data capture (CDC) workload, directly addressing the bottleneck that causes replication lag. When the source Oracle RDS generates a high volume of transactions, a smaller instance like t3.medium can become CPU or memory constrained, leading to a backlog in applying changes to the S3 target. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding that DMS performance is primarily limited by the replication instance’s compute capacity, not by source storage or target format changes. A common trap is to assume that converting the target to Parquet or increasing source storage will help, but these either add overhead or do not affect DMS throughput. Memory tip: “Bigger instance, faster persistence”—scale the DMS instance before touching the source or target.
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. 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 Database Migration Service (DMS) to continuously replicate data from an Oracle RDS instance to S3. The data is used for analytics. The replication lags behind the source by several hours. Which change would most likely reduce the lag?
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
✓
Use a larger DMS replication instance (e.g., dms.c5.large instead of dms.t3.medium).
Option A is correct because using a larger instance provides more CPU and memory for DMS. Option B is wrong because S3 endpoint cannot be changed to Kinesis without redesign. Option C is wrong because increasing source RDS storage doesn't directly impact DMS performance. Option D is wrong because changing target to Parquet adds transformation overhead.
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.
✗
Change the target endpoint from S3 to Kinesis Data Firehose.
Why it's wrong here
Firehose eventually writes to S3, but adds another hop.
✗
Increase the source RDS instance storage to improve I/O.
Why it's wrong here
Source performance is rarely the bottleneck for CDC.
✓
Use a larger DMS replication instance (e.g., dms.c5.large instead of dms.t3.medium).
The clue word "most likely" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
✗
Change the target data format from CSV to Parquet.
Why it's wrong here
Parquet transformation adds overhead.
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 DEA-C01 ACL questions on filtering logic and placement.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Use a larger DMS replication instance (e.g., dms.c5.large instead of dms.t3.medium). — Option A is correct because using a larger instance provides more CPU and memory for DMS. Option B is wrong because S3 endpoint cannot be changed to Kinesis without redesign. Option C is wrong because increasing source RDS storage doesn't directly impact DMS performance. Option D is wrong because changing target to Parquet adds transformation overhead.
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.
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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