The answer is to use AWS Database Migration Service (DMS) with ongoing replication. This is correct because DMS performs a full load of the 2 TB Oracle database to Amazon RDS, then uses change data capture (CDC) to continuously replicate incremental changes from the source, allowing you to cut over in minutes rather than hours—critical when you only have a 4-hour maintenance window. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of minimizing downtime during large migrations; a common trap is choosing AWS Snowball or a simple one-time DMS full load, which would exceed the window. Remember that “ongoing replication” is the key phrase for near-zero downtime, and think of it as “full load plus continuous trickle feed.” A helpful memory tip: DMS with CDC = “Don’t Miss a Single change.”
DBS-C01 Deployment and Migration Practice Question
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 2 TB Oracle database from on-premises to Amazon RDS for Oracle. The database has a 4-hour maintenance window and the migration must have minimal downtime. Which AWS service should be used for the migration?
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 the source database.
AWS DMS with ongoing replication (change data capture) is the correct choice because it allows you to perform a full load of the 2 TB Oracle database and then continuously replicate incremental changes from the source to the target RDS instance. This minimizes downtime by enabling a cutover window of minutes rather than hours, which is critical given the 4-hour maintenance window constraint.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 Schema Conversion Tool (SCT) to convert the schema and then perform a full data load.
Why it's wrong here
SCT only converts schema; it does not handle data migration with minimal downtime.
✗
Create an RDS Cross-Region Read Replica and promote it to a standalone instance.
Why it's wrong here
Cross-Region Read Replicas are for disaster recovery, not for migrating on-premises databases.
✓
Use AWS Database Migration Service (DMS) with ongoing replication from the source database.
Why this is correct
AWS DMS can perform continuous replication, minimizing downtime.
Related concept
Read the scenario before looking for a memorised answer.
✗
Take a full backup of the on-premises database, upload it to S3, and restore it to RDS.
Why it's wrong here
This approach requires downtime for the backup and restoration, not minimal downtime.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse AWS SCT with DMS, assuming SCT can handle ongoing replication, or they mistakenly think RDS Cross-Region Read Replicas can be created from an on-premises source, when in fact they only work between RDS instances.
Detailed technical explanation
How to think about this question
AWS DMS uses Oracle LogMiner or binary reader to capture change data from the source database's redo logs, enabling near-real-time replication with sub-second latency. For a 2 TB database, the full load phase may take several hours, but ongoing replication ensures that during the cutover, only the final seconds of changes need to be applied, keeping downtime minimal. In real-world scenarios, DMS can handle large LOBs and compression, but you must ensure the source database has supplemental logging enabled for all columns to capture complete changes.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Deployment and Migration — This question tests Deployment and Migration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use AWS Database Migration Service (DMS) with ongoing replication from the source database. — AWS DMS with ongoing replication (change data capture) is the correct choice because it allows you to perform a full load of the 2 TB Oracle database and then continuously replicate incremental changes from the source to the target RDS instance. This minimizes downtime by enabling a cutover window of minutes rather than hours, which is critical given the 4-hour maintenance window constraint.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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