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If you would like to sync any attribute which does not supports direct sync, you would need to use Directory Extension Attribute Sync: https://docs.microsoft.com/en-us/azure/active-directory/hybrid/reference-connect-sync-attributes-synchronized.
When you use "Directory Extension Attributes" in AD Connect Server these new attributes are synced to AAD. However, these new Attributes would not be visible on GUI.
- When you setup Directory Extension Attribute Sync there is no downtime or impact on users, however Azure AD connect wizard may prompt to perform full sync, which can be unchecked if needed.
- In below screenshot is an example of Employee Type and Division Attribute and Nationality which are sync'd to Azure AD as an Directory extension attribute.
- Attributes sync'd using Directory Extension Attribute Sync would not be visible on user profile on Azure AD Portal/GUI.
- You would need to use Graph to query and view these attributes on the users in AAD.
- Below is the screenshot which confirm the successful sync to Azure AD.
- Following documentation link has more details about Directory Extension Attributes: https://learn.microsoft.com/en-us/azure/active-directory/hybrid/connect/how-to-connect-sync-feature-directory-extensions
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