Quick Answer
The answer is AWS Database Migration Service (DMS). For a minimal downtime Oracle migration to RDS using DMS, DMS is the correct choice because it supports both a full initial data load and ongoing change data capture (CDC) replication, allowing you to keep the source and target databases synchronized during the cutover window. This means you can migrate the 500 GB Oracle database while continuously applying transactions from the source, reducing downtime to just a brief final switchover. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your understanding of migration strategies and the distinction between offline and online tools—a common trap is choosing Snowball for large datasets, but that is an offline, batch-only method with no replication capability. Remember the key: if the scenario demands minimal downtime, look for a service that offers both full load and ongoing replication, and DMS is the only AWS service that provides CDC for database migrations. Memory tip: “DMS Does Minimal Stops” for full load plus continuous replication.
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 500 GB on-premises Oracle database to Amazon RDS for Oracle. The migration must have minimal downtime. Which AWS service should be used for the initial data load and ongoing replication?
AWS Snowball Edge for offline data transfer
Why wrong: Snowball is offline and cannot achieve minimal downtime.
AWS Database Migration Service (AWS DMS)
DMS supports full load and CDC replication for minimal downtime.
Amazon S3 to store backup files and restore
Why wrong: S3 alone does not provide ongoing replication.
AWS DataSync
Why wrong: DataSync is designed for file-based data, not databases.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AWS Database Migration Service (AWS DMS)
AWS Database Migration Service (DMS) supports both full load and ongoing replication from Oracle to RDS Oracle, enabling minimal downtime migrations. Option A (S3) does not provide replication. Option B (Snowball) is offline. Option D (DataSync) is for file data, not databases.
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
For each option: why learners choose it and why it is or isn't the right answer here.
AWS Snowball Edge for offline data transfer
Why it's wrong here
Snowball is offline and cannot achieve minimal downtime.
AWS Database Migration Service (AWS DMS)
Why this is correct
DMS supports full load and CDC replication for minimal downtime.
Related concept
Standard ACLs match source addresses.
Amazon S3 to store backup files and restore
Why it's wrong here
S3 alone does not provide ongoing replication.
AWS DataSync
Why it's wrong here
DataSync is designed for file-based data, not databases.
Common exam traps
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
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.
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
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
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 DBS-C01 ACL questions on filtering logic and placement.
Deployment and Migration — study guide chapter
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FAQ
Deployment and Migration — This question tests Deployment and Migration — Standard ACLs match source addresses..
The correct answer is: AWS Database Migration Service (AWS DMS) — AWS Database Migration Service (DMS) supports both full load and ongoing replication from Oracle to RDS Oracle, enabling minimal downtime migrations. Option A (S3) does not provide replication. Option B (Snowball) is offline. Option D (DataSync) is for file data, not databases.
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 DBS-C01 ACL questions on filtering logic and placement.
Standard ACLs match source addresses.
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Same concept, more angles
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Variation 1. A company is migrating a 10 TB Oracle database to Amazon RDS for Oracle. The migration window is limited to 24 hours. The source database is running on-premises with a 500 Mbps network connection. Which migration approach should be used?
mediumWhy A: Option A is correct because AWS DMS with ongoing replication can handle large data volumes and minimize downtime by continuously replicating changes. Option B is wrong because Oracle Data Pump is a manual export/import process that requires downtime and may not complete within 24 hours if the network is slow. Option C is wrong because the source is on-premises, not an EC2 instance, so a read replica cannot be created. Option D is wrong because taking a backup and restoring to RDS requires the backup to be transferred to S3 first, which may be time-consuming.
Last reviewed: Jun 20, 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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