DEA-C01 Data Ingestion and Transformation Practice Question
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?
⚠ Common exam trap
Test-takers frequently assume the lag is caused by the target (S3 write performance or format) or source database I/O, rather than recognizing that DMS replication instance sizing is the primary bottleneck for CDC throughput.
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
✓
Use a larger DMS replication instance (e.g., dms.c5.large instead of dms.t3.medium).
The replication lag is most likely caused by the DMS replication instance being undersized for the volume of change data capture (CDC) events. Upgrading from a burstable t3.medium to a compute-optimized c5.large instance provides more consistent CPU performance and higher network throughput, enabling faster processing of Oracle redo logs and reducing the lag between source and target.
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).
Why this is correct
More compute resources reduce lag.
- ✗
Change the target data format from CSV to Parquet.
Why it's wrong here
Parquet transformation adds overhead.
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 |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-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 DEA-C01 exam.