How to Migrate to Azure SQL Database with Minimal Downtime Using Azure Database Migration Service
A company plans to migrate a 500 GB SQL Server database from on-premises to Azure SQL Database. They require minimal downtime during the migration. Which approach should they use?
Quick Answer
The answer is to use Azure Database Migration Service with online migration mode. This is the correct approach because online migration mode leverages transactional replication to continuously synchronize ongoing changes from the source SQL Server to Azure SQL Database, allowing the source database to remain fully operational throughout the process. Only a brief cutover is required at the end, which keeps downtime to an absolute minimum. On the Microsoft Azure Data Fundamentals DP-900 exam, this question tests your understanding of migration strategies and the distinction between offline and online methods. A common trap is choosing offline migration, which requires taking the source database offline for the entire duration, resulting in significant downtime. To remember this, think of the keyword “minimal downtime” as your cue for “online”—if the scenario demands near-zero interruption, always select the online migration mode.
⚠ Common exam trap
Many exam-takers confuse offline backup/restore or BACPAC methods (which are simpler but cause downtime) with the online migration capability of DMS, assuming any Azure tool can achieve minimal downtime without understanding the underlying replication mechanism.
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 Azure Database Migration Service with online migration mode
Azure Database Migration Service (DMS) with online migration mode is the correct approach because it supports minimal-downtime migrations by continuously replicating ongoing changes from the source SQL Server to Azure SQL Database using the transactional replication technology. This allows the source database to remain operational during the migration, and only a brief cutover is needed at the end to switch applications to the 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.
- ✗
Export a BACPAC file and import to Azure SQL Database
Why it's wrong here
Incorrect. BACPAC export/import is offline, causing downtime as the database is locked during export.
When this WOULD be correct
A company needs to migrate a small database (e.g., under 100 GB) to Azure SQL Database and can tolerate several hours of downtime. The BACPAC method is simple and does not require additional Azure services.
- ✓
Use Azure Database Migration Service with online migration mode
Why this is correct
Correct. Online migration via DMS synchronizes changes in near real-time, allowing the source to stay online until cutover, minimizing downtime.
- ✗
Use Azure Site Recovery to replicate the database
Why it's wrong here
Incorrect. Azure Site Recovery is designed for disaster recovery of entire VMs, not for database schema and data migration with minimal downtime.
When this WOULD be correct
A company needs to migrate an entire on-premises SQL Server instance (including multiple databases and server-level objects) to Azure VMs with minimal downtime for disaster recovery purposes. Azure Site Recovery would be the correct choice for replicating the entire server.
- ✗
Create a full database backup and restore to Azure SQL Database
Why it's wrong here
Incorrect. Restoring a full backup is an offline process that requires the source database to be closed, causing significant downtime.
When this WOULD be correct
This approach would be correct if the question specified that the database is small (e.g., under 200 GB), the migration can tolerate several hours of downtime, and the company wants a simple, low-cost method without additional Azure services.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The DP-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Use Azure Database Migration Service with online migration modeCorrect answer▾
Why this is correct
Correct. Online migration via DMS synchronizes changes in near real-time, allowing the source to stay online until cutover, minimizing downtime.
✗Export a BACPAC file and import to Azure SQL DatabaseWrong answer — click to see why▾
Why this is wrong here
Exporting a BACPAC file requires the database to be online and can cause significant downtime due to data export and import times, especially for a 500 GB database. It does not support minimal downtime migration.
★ When this WOULD be the correct answer
A company needs to migrate a small database (e.g., under 100 GB) to Azure SQL Database and can tolerate several hours of downtime. The BACPAC method is simple and does not require additional Azure services.
Why candidates choose this
Candidates may think BACPAC is the standard migration tool for Azure SQL Database, overlooking its limitations for large databases and minimal downtime requirements.
✗Use Azure Site Recovery to replicate the databaseWrong answer — click to see why▾
Why this is wrong here
Azure Site Recovery is designed for disaster recovery and replication of entire VMs or physical servers, not for online migration of a single database with minimal downtime. It would replicate the entire server environment, which is overkill and not optimized for database migration.
★ When this WOULD be the correct answer
A company needs to migrate an entire on-premises SQL Server instance (including multiple databases and server-level objects) to Azure VMs with minimal downtime for disaster recovery purposes. Azure Site Recovery would be the correct choice for replicating the entire server.
Why candidates choose this
Candidates may think Site Recovery can handle database migration because it provides replication and failover capabilities, but they overlook that it is not a database-specific migration tool and does not support online migration to Azure SQL Database.
✗Create a full database backup and restore to Azure SQL DatabaseWrong answer — click to see why▾
Why this is wrong here
Creating a full database backup and restoring to Azure SQL Database requires the source database to be offline or in read-only mode during the backup, causing significant downtime. This does not meet the minimal downtime requirement.
★ When this WOULD be the correct answer
This approach would be correct if the question specified that the database is small (e.g., under 200 GB), the migration can tolerate several hours of downtime, and the company wants a simple, low-cost method without additional Azure services.
Why candidates choose this
Candidates are familiar with backup and restore operations from on-premises SQL Server and may assume this straightforward method can be used with minimal downtime, overlooking the fact that Azure SQL Database does not support native restore from a full backup without downtime.
Analysis generated from the official DP-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Azure SQL Services
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
Key term
Azure SQL Database
Azure SQL Database is a fully managed relational database-as-a-service (DBaaS) in Microsoft Azure, based on the SQL Server engine, that handles scaling, backups, patching, and high availability automatically.
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Same concept, more angles
2 more ways this is tested on DP-900
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company needs to migrate a large on-premises SQL Server database to Azure with minimal downtime. Which Azure service should they use for the migration?
easy- A.Azure SQL Database
- B.Azure Backup
- C.Azure Data Factory
- ✓ D.Azure Database Migration Service
Why D: Azure Database Migration Service (DMS) is designed for online migrations with minimal downtime, supporting continuous data sync. Option A is wrong because Azure SQL Database is the target, not a migration tool. Option B is wrong because Azure Backup is for backup, not migration. Option C is wrong because Azure Data Factory is for data integration, not database migration with minimal downtime.
Variation 2. A company needs to migrate a large on-premises SQL Server database to Azure. The migration must have minimal downtime and support ongoing replication. Which Azure service should they use?
easy- A.Azure Data Box
- B.Azure Data Factory
- C.Azure SQL Database
- ✓ D.Azure Database Migration Service
Why D: Azure Database Migration Service (DMS) is designed for online migrations with minimal downtime, supporting ongoing replication from SQL Server to Azure SQL Database. It uses the Data Migration Assistant (DMA) for assessment and the Azure DMS for continuous sync, enabling near-zero downtime during cutover.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-900 practice question is part of Courseiva's free Microsoft 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 DP-900 exam.