DBS-C01 Deployment and Migration Practice Question
A company is migrating a 2 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL with minimal downtime. The database is continuously updated. Which migration strategy should be used?
⚠ Common exam trap
Test-takers frequently assume pg_dump/pg_restore or full-load-only DMS are sufficient for minimal downtime, but they fail to account for the continuous updates that require ongoing replication to avoid data loss.
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 AWS Database Migration Service (DMS) with ongoing replication from an on-premises source.
AWS DMS supports ongoing replication (change data capture, CDC) from an on-premises PostgreSQL source to Amazon RDS for PostgreSQL, enabling minimal downtime migration. The 2 TB size is well within DMS's capabilities, and CDC captures incremental changes after the full load, allowing near-zero downtime cutover.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use AWS Database Migration Service (DMS) with ongoing replication from an on-premises source.
Why this is correct
DMS with change data capture (CDC) allows continuous replication with minimal downtime.
- ✗
Use AWS Schema Conversion Tool (SCT) and AWS Snowball to transfer data.
Why it's wrong here
SCT with Snowball is for schema conversion and large bulk transfers, not for minimal-downtime continuous replication.
- ✗
Use AWS Database Migration Service with a full load only, then cut over.
Why it's wrong here
Full load only does not capture ongoing changes; downtime would occur during cutover.
- ✗
Use pg_dump and pg_restore during a maintenance window.
Why it's wrong here
pg_dump/pg_restore requires downtime and cannot handle ongoing changes.
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Same concept, more angles
3 more ways this is tested on DBS-C01
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Variation 1. A company is migrating a 1 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. The migration must have minimal downtime. Which TWO steps should be taken to achieve this?
medium- ✓ A.Configure AWS DMS with ongoing replication from the source to the target.
- B.Use AWS SCT to convert the schema to Amazon Aurora.
- ✓ C.Use pglogical extension to replicate data from on-premises to RDS.
- D.Take a full backup using pg_dump and import it into RDS during a maintenance window.
- E.Create an RDS Read Replica of the on-premises database.
Why A: AWS DMS with ongoing replication (change data capture, CDC) allows continuous synchronization from the on-premises PostgreSQL source to the RDS target, enabling a cutover with minimal downtime. DMS captures incremental changes using PostgreSQL's logical replication slots, so only a brief outage is needed to stop writes and finalize the migration. Similarly, the pglogical extension provides logical replication directly from on-premises PostgreSQL to RDS for PostgreSQL, also enabling continuous syncing and minimal downtime. Both options A and C achieve the goal of minimal downtime by allowing a full load plus ongoing replication.
Variation 2. A company is migrating a 2 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. The database has a 4-hour downtime window. The company requires minimal data loss and wants to use AWS DMS. The on-premises network has a 100 Mbps internet connection. Which migration method should the company use?
medium- A.Use AWS Schema Conversion Tool (SCT) to migrate the data to Amazon RDS.
- B.Use AWS DMS with a full load only, then stop the source database and resume applications.
- C.Use pg_dump and pg_restore to export and import the database during the downtime window.
- ✓ D.Use AWS DMS with a full load and ongoing change data capture (CDC) replication.
Why D: AWS DMS with a full load and ongoing change data capture (CDC) replication allows the company to migrate the 2 TB database with minimal data loss within the 4-hour downtime window. The full load transfers the existing data, and CDC captures and applies ongoing changes from the source database to the target RDS instance, reducing the final cutover downtime to seconds or minutes. This approach is ideal for large databases with tight downtime constraints and limited bandwidth (100 Mbps), as the initial full load can run before the downtime window, and only the final CDC catch-up occurs during the window.
Variation 3. A company is migrating a 2 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. The migration must have minimal downtime and support ongoing replication. Which AWS service should be used for the migration?
medium- A.AWS S3 Transfer Acceleration for direct database export
- B.AWS Data Migration Service with AWS Glue
- C.AWS Snowball Edge for offline data transfer
- ✓ D.AWS Database Migration Service (DMS) with change data capture
Why D: AWS Database Migration Service (DMS) with change data capture (CDC) is the correct choice because it supports ongoing replication from the source PostgreSQL database to Amazon RDS for PostgreSQL with minimal downtime. DMS performs a full load of the 2 TB database and then continuously applies changes using PostgreSQL's logical replication slots (via the pglogical extension or native WAL-based CDC), ensuring the target remains synchronized during the migration cutover.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.