DEA-C01 Data Ingestion and Transformation Practice Question
A data engineering team is using AWS DMS to migrate a 2 TB Oracle database to Amazon RDS for PostgreSQL. The migration must have minimal downtime and needs to capture ongoing changes after the full load. Which THREE resources are required for this task? (Choose three.)
⚠ Common exam trap
DEA-C01 often tests whether candidates confuse DMS's core three-component architecture (source endpoint, target endpoint, replication instance) with optional services like S3 staging or Snowball that are only relevant for specific migration patterns.
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
✓
A DMS source endpoint configured for Oracle.
Option A is correct because AWS DMS requires a source endpoint that defines the Oracle database connection details, including server name, port, SID/service name, and credentials, so the replication instance can read the full load data and ongoing redo/archive log changes. Option B is correct because the AWS DMS replication instance is the managed compute resource that actually runs the migration tasks, performs the full load, and applies change data capture (CDC) from Oracle to the target. Option E is correct because a target endpoint pointing to the Amazon RDS for PostgreSQL instance is mandatory so DMS knows where to write the migrated tables and replicated changes. Option C is not needed because Snowball Edge is an offline physical transfer device, whereas DMS performs the migration over the network and supports ongoing replication. Option D is not required because DMS does not need an Amazon S3 staging bucket for an Oracle-to-RDS PostgreSQL migration; S3 is only used for certain source/target types such as S3 endpoints or specific native backup/restore workflows.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A DMS source endpoint configured for Oracle.
Why this is correct
Oracle is the migration source, so a DMS source endpoint must define connection details and credentials for the Oracle database. This endpoint lets the replication instance read the full load and, with change data capture enabled, ongoing redo log changes, satisfying the minimal-downtime requirement.
- ✓
An AWS DMS replication instance.
Why this is correct
The replication instance is the managed compute that runs the migration task, connecting source and target endpoints. It performs the full load of the 2 TB database and then applies ongoing change data capture, which is what delivers the required minimal downtime.
- ✗
An AWS Snowball Edge device for initial data transfer.
Why it's wrong here
Snowball Edge suits offline bulk transfer of terabytes where network bandwidth is constrained, but DMS performs the full load and ongoing change capture over the network with minimal downtime. It is tempting for large datasets, yet it cannot capture ongoing changes after the load.
- ✗
An Amazon S3 bucket for staging the data.
Why it's wrong here
DMS uses the target endpoint directly for both full load and ongoing replication; an S3 staging bucket is unnecessary for native Oracle-to-PostgreSQL migration. It is tempting because S3 commonly stages data for services like Snowball or Athena, but DMS's change data capture writes straight to RDS.
- ✓
A DMS target endpoint configured for Amazon RDS PostgreSQL.
Why this is correct
Amazon RDS for PostgreSQL is the migration destination, so a DMS target endpoint is required to define its connection settings. The replication instance writes both the initial full load and subsequent change data capture events into PostgreSQL through this endpoint.
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 and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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.