Azure AD Connect Best Practices

Deploying and managing Azure AD Connect is a critical step for organizations looking to synchronize their on-premises Active Directory with Azure Active Directory. Following best practices ensures reliability, security, and performance. This post outlines key considerations for a robust Azure AD Connect implementation.

1. Planning and Preparation

a. Server Requirements

Ensure your server meets or exceeds the minimum hardware and software requirements for Azure AD Connect. This includes:

Adequate CPU and RAM, especially for large environments.
Sufficient disk space for logging and temporary files.
A supported operating system version.
.NET Framework and PowerShell versions.

b. Network Connectivity

Verify that the server can communicate with both your on-premises domain controllers and the Azure AD endpoints. Ensure necessary firewall rules are in place, allowing outbound traffic on specific ports and URLs.

2. Installation and Configuration

a. Express Settings vs. Custom Settings

For most scenarios, the Express Settings are sufficient. However, if you have specific requirements like synchronizing multiple forests, filtering specific OUs, or using alternate login IDs, choose Custom Settings. Always document your configuration choices.

b. Service Account Management

Azure AD Connect uses a managed service account for its operations. Avoid using a custom service account unless absolutely necessary and ensure it has the correct permissions. Regularly review its membership and permissions.

c. Synchronization Rules

Understand the default synchronization rules. Before making custom changes, use the Synchronization Rules Editor to analyze existing rules and their precedence. Customizations should be well-documented and tested thoroughly.

Important: Start with the default rules and only create custom rules when the default behavior doesn't meet your requirements. Document any custom rules and their purpose.

3. Ongoing Management and Monitoring

a. Enable Staging Mode for Changes

When performing significant configuration changes, upgrades, or testing custom rules, enable staging mode. This allows you to review the synchronization results without actually exporting them to Azure AD, preventing unintended consequences.

To enable staging mode:

Import-Module ADSync
Set-ADSyncStagingMode -Enable $true

b. Regular Health Checks

Utilize the Synchronization Service Manager to monitor synchronization cycles, identify errors, and review pending exports. Schedule regular checks and investigate any warnings or errors promptly.

c. Azure AD Connect Health Agent

Install and configure the Azure AD Connect Health agent. This provides proactive monitoring, alerts, and performance insights for your synchronization service and identity infrastructure directly within the Azure portal.

d. Password Hash Synchronization (PHS) Considerations

If using PHS, ensure it's enabled and functioning correctly. PHS is the simplest and most recommended sign-in method. For seamless SSO, consider implementing Seamless Single Sign-On alongside PHS.

4. Security Best Practices

a. Server Hardening

Treat the Azure AD Connect server as a critical infrastructure component. Apply standard server hardening techniques, including:

Minimizing installed software.
Enforcing strong password policies for administrative accounts.
Configuring Windows Firewall.
Regularly applying security patches and updates.

b. Access Control

Restrict administrative access to the Azure AD Connect server to a minimal number of authorized personnel. Use dedicated administrative accounts and avoid logging in with domain administrator credentials directly on the server.

c. Avoid Installing Other Applications

Do not install other applications (like SQL Server, Exchange, or third-party agents) on the Azure AD Connect server. This reduces the attack surface and prevents potential conflicts.

                Recommendation: Dedicate a server solely for Azure AD Connect to ensure optimal performance and security.
            

5. Disaster Recovery and High Availability

a. Backup and Restore

Regularly back up the Azure AD Connect configuration. This allows for quick restoration in case of server failure or data corruption.

You can export the configuration using PowerShell:

Import-Module ADSync
Export-ADSyncServerConfiguration -Path "C:\ADSyncConfigBackup"

b. Staging Server for High Availability

For larger or mission-critical environments, consider setting up a second Azure AD Connect server in staging mode. This server can be promoted to active if the primary server fails, providing high availability.

Conclusion

Implementing Azure AD Connect with these best practices in mind will significantly enhance the security, reliability, and manageability of your hybrid identity solution. Continuous monitoring and proactive maintenance are key to ensuring a seamless user experience and robust security posture.