Azure Migrate vs Database Migration Service: What AZ-305 Expects

For AZ-305, the clean boundary is this: use Azure Migrate when the scenario asks you to discover an estate, assess readiness, estimate sizing and cost, or choose an Azure SQL target. Use Azure Database Migration Service when the target has already been chosen and the problem is migrating database data with the right online or offline path. Microsoft describes Azure Migrate as the hub for discovery, assessment, and migration across servers, databases, web apps, virtual desktops, and data, while Database Migration Service is the managed migration service for moving databases to Azure data platforms (Azure Migrate overview, DMS overview).

That distinction matters because AZ-305 is not asking you to memorize product names. Microsoft lists "Design infrastructure solutions" at 30-35% of the exam, and the study guide includes migration evaluation, on-premises servers, data, applications, and recommendations for IaaS and PaaS migration paths (AZ-305 exam page, AZ-305 study guide). In a database scenario, the answer usually turns on whether you are still assessing the estate or already executing the move.

Compact decision shortcut

Choose Azure Migrate when the question says assess, discover, readiness, dependency, sizing, cost, or target recommendation. For SQL Server, Azure Migrate assessments evaluate readiness for targets such as Azure SQL Database, Azure SQL Managed Instance, and SQL Server on Azure VMs, and they can estimate sizing and cost from collected metadata (SQL assessment calculations, SQL assessment tutorial).

Choose Database Migration Service when the question says migrate, replicate, online migration, offline migration, cutover, or move data after the target is selected. Microsoft positions DMS as a service for database migration to Azure with minimal downtime options, available through the Azure portal, PowerShell, and Azure CLI (DMS overview, DMS automation).

Do not use DMS as the assessment answer. If a case study asks for an Azure SQL target recommendation or readiness report, DMS is too late in the lifecycle. Do not use Azure Migrate alone as the execution answer when the scenario is explicitly about running the database migration and cutover path.

The flow AZ-305 is testing

Read the diagram from left to right. Azure Migrate belongs in the inventory-and-assess phase. It helps you understand what exists, whether the SQL estate can land on an Azure SQL target, what sizing looks like, and where blockers need remediation. The execution phase begins only after the target and migration approach are clear.

That is why a tool-boundary answer often beats a broad migration-strategy answer. The exam may describe an on-premises SQL Server estate and ask for the best tool to evaluate readiness for Azure SQL Managed Instance. Pick Azure Migrate. If the same estate already has a selected managed instance target and the requirement is near-zero downtime migration, the answer moves toward a migration execution service and workflow.

What Azure Migrate contributes before the move

Azure Migrate is not just "the VM migration tool." Microsoft describes it as a central hub for discovery, assessment, and migration/modernization across workload types, including servers and databases (Azure Migrate overview). In AZ-305 wording, that makes it the stronger answer when the architect still needs evidence.

For SQL Server specifically, an Azure SQL assessment can produce readiness and sizing guidance for Azure SQL Database, Azure SQL Managed Instance, and SQL Server on Azure VMs. The assessment logic considers collected configuration, performance data, feature compatibility, target sizing, and estimated monthly cost depending on the assessment settings (SQL assessment calculations).

This is the planning value: Azure Migrate can tell you that one database is ready for Azure SQL Database, another is a better fit for managed instance because of instance-level dependencies, and another may need SQL Server on Azure VMs because the compatibility or operational requirements do not fit PaaS cleanly. That is a target recommendation problem, not a cutover problem.

What Database Migration Service contributes during execution

Database Migration Service sits later. Microsoft describes DMS as a managed service for migrations from multiple database sources to Azure data platforms, with support for online and offline migrations depending on source and target (DMS overview). Microsoft also documents DMS automation through PowerShell and Azure CLI for database migrations at scale, including configuring online migration and cutover workflows (DMS automation).

That means DMS is the better AZ-305 answer when the question already says the destination is Azure SQL Managed Instance or Azure SQL Database and the architect must select the migration execution mechanism. It is especially likely when the stem mentions data movement, ongoing replication, a migration project, migration runtime, downtime window, or cutover validation.

The mistake is treating DMS as if it discovers the whole environment and decides the target for you. Microsoft documentation separates migration guidance and service execution from the assessment calculations that Azure Migrate provides for SQL targets (Azure SQL migration guides, SQL assessment calculations).

One current-source caution: older study material may mention the Azure SQL migration extension for Azure Data Studio. Azure Data Studio is retired as of February 28, 2026, and Microsoft says it no longer receives updates or security fixes (Azure Data Studio retirement). For a 2026-facing article, use the current DMS portal, PowerShell, and CLI framing instead of recommending Azure Data Studio as the default.

Worked example: the tool boundary in one case study

Suppose a company has 80 on-premises SQL Server databases. The architecture team knows it wants to modernize, but it does not yet know which databases can move to Azure SQL Database, which need Azure SQL Managed Instance, and which should stay on SQL Server running on Azure VMs. Leadership also wants a cost estimate before approving the migration wave.

The best first answer is Azure Migrate. The requirement is assessment: discover the SQL estate, evaluate readiness, identify blockers, recommend targets, estimate sizing, and produce a defensible migration wave plan. DMS would be premature because no target or execution path has been approved.

Now change the stem. The same company completed assessment, selected Azure SQL Managed Instance for a business-critical database, and needs to migrate with minimal downtime. The best answer shifts. You would use an execution workflow such as Azure Database Migration Service through the Azure portal, PowerShell, or Azure CLI. Azure Migrate helped decide the destination; DMS helps move the database.

Exam-ready sentence: Azure Migrate answers "what do we have, where should it go, and what will block us?" DMS answers "how do we move this database to the selected Azure target?"

Common wrong-answer patterns

Picking DMS for target selection. If the stem says "recommend the best Azure SQL option" or "assess readiness," DMS is not the clean answer. Use Azure Migrate because Microsoft documents SQL assessments for readiness, target sizing, and cost.

Picking Azure Migrate for every database migration. Azure Migrate is a hub, but the execution tool still matters. When the scenario is already past assessment and asks for online or offline migration mechanics, choose the database migration workflow.

Ignoring SQL Server on Azure VMs. AZ-305 scenarios may include compatibility, instance-level features, OS-level control, or operational constraints. Azure Migrate assessments can compare Azure SQL Database, Azure SQL Managed Instance, and SQL Server on Azure VMs, so do not force every assessed database into PaaS.

Turning this into a general migration strategy question. Rehost, replatform, refactor, and rearchitect are adjacent concepts, but this article's boundary is narrower: assessment/readiness/target recommendation versus migration execution/orchestration. If the question is about strategy depth, use a strategy framework. If it is about SQL readiness and migration tooling, use the tool boundary.

How to practice this for AZ-305

When you review a migration question, underline the lifecycle verb first. If the verb is assess, discover, evaluate, estimate, or recommend, start with Azure Migrate. If the verb is migrate, replicate, cut over, or minimize downtime during the move, start with DMS or the documented Azure SQL migration execution path.

Then identify the target uncertainty. If the target is uncertain, Azure Migrate is usually still in play. If the target is explicit, such as "migrate this SQL Server database to Azure SQL Managed Instance," the question is probably testing execution.

Finally, check whether the scenario is database-specific or workload-wide. Azure Migrate can evaluate broader estates. DMS is narrower and database-migration-specific. That is exactly why the two tools are easy to confuse and why the distinction is exam-useful.

Where CramHQ fits

CramHQ is not a Microsoft product and does not guarantee a pass. For this topic, it can help you turn a missed migration-tool question into a focused learning loop: identify whether the miss came from assessment scope, target selection, Azure SQL service fit, downtime wording, or execution mechanics, then practice nearby scenarios until the boundary is automatic.

When you are ready, take the AZ-305 assessment. After each missed migration question, write one sentence: "I chose the wrong tool because the scenario was really asking for ____." Fill the blank with assessment, recommendation, migration execution, or cutover, then retest that exact weakness.

Quick recap

• Azure Migrate is the stronger answer for discovery, readiness, sizing, cost, dependency, and target recommendation.
• Azure SQL assessments can evaluate readiness for Azure SQL Database, Azure SQL Managed Instance, and SQL Server on Azure VMs.
• Database Migration Service is the stronger answer for database migration execution after the target is known.
• DMS is available through the Azure portal, PowerShell, and Azure CLI.
• Treat old Azure Data Studio migration-extension guidance as stale unless the question or source explicitly scopes it to that retired tool.
• AZ-305 usually rewards lifecycle clarity: assess first, execute after the target and blockers are understood.