What Is Active Directory to Entra ID Synchronization?

Organizations that have used Windows Server and Active Directory for years often need a way to connect their existing identities with Microsoft 365 and other cloud applications.

That is where Active Directory to Entra ID synchronization comes in.The synchronization process connects an on-premises directory with Microsoft Entra ID, allowing selected identity information to
be represented in the cloud. Microsoft documents both Microsoft Entra Connect Sync and Microsoft Entra Cloud Sync as synchronization technologies for hybrid identity scenarios. Cloud Sync uses the Microsoft Entra provisioning agent and a cloud-based provisioning service, while Connect Sync uses an on-premises synchronization engine.

What You’ll Need

Before implementing synchronization, understand the environment rather than
installing a synchronization tool immediately.

• Working Active Directory Domain Services environment.
• Administrative access appropriate for the selected synchronization tool.
• A Microsoft Entra tenant.
• Verified and correctly configured domains where required.
• Network connectivity required by the selected Microsoft service.
• A documented synchronization scope.
• A defined source of authority for identity attributes.
• A recovery and rollback plan.

Which Synchronization Tool Should You Use?

Microsoft currently provides two important synchronization approaches: Microsoft Entra Connect Sync and
Microsoft Entra Cloud Sync.

Microsoft describes Cloud Sync as its strategic direction for hybrid identity
synchronization as functional parity is reached. However, organizations should
evaluate their actual topology and required features before migrating.

How Active Directory to Entra ID Synchronization Works

Although the underlying architecture can become complex, the basic process can be understood in five stages.

1. Collect

The synchronization technology reads supported identity information from. Active Directory.

2. Evaluate

The synchronization configuration determines which objects and attributes are inside the configured scope.

3. Transform

Configured synchronization rules and attribute mappings determine how source directory information is represented in the target identity system.

4. Provision

The synchronization service provisions supported objects and attributes into Microsoft Entra ID.

5. Monitor

Administrators monitor synchronization health, errors, provisioning status and authentication dependencies.

Active Directory
       |
       v
Synchronization Scope
       |
       v
Attribute Mapping
       |
       v
Synchronization Engine
       |
       v
Microsoft Entra ID
       |
       v
Microsoft 365 / Cloud Applications

What Gets Synchronized?

The exact objects and attributes depend on the selected synchronization. technology and configuration.

Common identity objects include:

• Users
• Groups
• Contacts
• Selected directory attributes

A critical point is that having an object in Active Directory does not automatically mean it will appear in Microsoft Entra ID.  Synchronization scope and rules determine what is processed.

Real-World Example: Synchronizing a New User

Imagine an administrator creates a new employee account in an Organizational. Unit called Employees.

1. The administrator creates the user in Active Directory.
2. The user falls within the configured synchronization scope.
3. The synchronization system evaluates the object’s attributes.
4. The object is provisioned into Microsoft Entra ID.
5. The administrator verifies the resulting cloud identity.
6. Appropriate Microsoft 365 licensing and application access can then be
   configured separately.

How Does Password Synchronization Work?

Password synchronization and directory-object synchronization are related but. different functions.

With Password Hash Synchronization (PHS), password-derived. information is synchronized so Microsoft Entra ID can perform cloud. authentication without synchronizing the user’s clear-text password.

Organizations can also use other authentication architectures, including Pass-through Authentication (PTA) and federation, depending on their requirements.

How to Configure Active Directory to Entra ID Synchronization

The exact configuration differs between Cloud Sync and Connect Sync, so use. Microsoft’s current prerequisites and deployment guidance for the selected. tool.

Step 1 — Review the Active Directory Environment

• Check domains and forests.
• Review Organizational Units.
• Identify user and group locations.
• Review duplicate or conflicting identities.
• Confirm required attributes.

Step 2 — Choose the Synchronization Technology

Use Microsoft’s current decision guidance to determine whether Cloud Sync or Connect Sync fits your environment.

Step 3 — Define Synchronization Scope

Avoid synchronizing unnecessary objects. Define the Organizational Units, groups or other supported scope that should be included.

Step 4 — Configure Attribute Mapping

Review how important Active Directory attributes map to Microsoft Entra ID.Pay particular attention to identity matching and sign-in attributes.

Step 5 — Configure Authentication

Select and configure the authentication architecture appropriate for the organization.

Step 6 — Pilot Before Production

Start with a controlled group of users whenever practical. Validate synchronization, sign-in, applications and user attributes before expanding the scope.

Step 7 — Monitor the Environment

After deployment, monitor synchronization status and errors instead of assuming the environment will remain healthy indefinitely.

Common Active Directory to Entra ID Synchronization Errors

Active Directory to Entra ID Synchronization Troubleshooting

When synchronization fails, avoid changing multiple settings at once. Troubleshoot from the source toward the cloud.

Advanced Hybrid Identity Considerations

Multiple Active Directory Forests

Organizations involved in mergers, acquisitions or complex enterprise. architectures may operate multiple forests.

Cloud Sync supports scenarios involving multiple disconnected forests that can. be difficult to address with traditional synchronization architectures.

Source of Authority

Before changing an identity attribute, determine which system is authoritative. If Active Directory is the source of authority for an attribute, changing the value directly in Microsoft Entra ID may not provide the long-term result you
expect.

Attribute Matching

Identity matching is particularly important when organizations have existing cloud accounts and begin synchronization. A poorly planned matching strategy can result in duplicate objects or
unexpected identity relationships.

Pros and Cons of Active Directory to Entra ID Synchronization

Best Practices

1. Start with a documented identity architecture.
2. Define the source of authority.
3. Keep synchronization scope as simple as practical.
4. Pilot changes before expanding synchronization.
5. Monitor synchronization health continuously.
6. Protect synchronization infrastructure.
7. Keep supported Microsoft components updated.
8. Document recovery and rollback procedures.
9. Review Cloud Sync eligibility as your environment evolves.

Related Articles

Frequently Asked Questions

Conclusion

Active Directory to Entra ID synchronization is one of the core building blocks of Microsoft 365 hybrid identity. The technology itself is straightforward at a high level:

The real engineering challenge is making that flow secure, predictable and. recoverable. Before deploying synchronization, understand your directory topology, define. your source of authority, choose the right synchronization technology, control. your synchronization scope and test the environment before production rollout.

For organizations already using Microsoft Entra Connect Sync, 2026 is also an important review point because Microsoft has published a mandatory minimum. version requirement for September 30, 2026.

Authoritative Sources

• Microsoft Learn — Microsoft Entra Cloud Sync
• Microsoft Learn — Microsoft Entra Connect Sync
• Microsoft Learn — Microsoft Entra synchronization tools
• Microsoft Learn — Microsoft Entra Connect prerequisites and upgrade requirements