Azure AD sync to on premise AD

Muhammad Qasim 

I would suggest to have your plan first, are you going to authenticate from local AD, or AAD? How about SSO, required? If yes, SSO with AAD or local AD?

Please refer below URL for your planning idea:

https://learn.microsoft.com/en-us/azure/architecture/reference-architectures/identity/azure-ad

Muhammad Qasim 

Hi, so the process of Azure AD connect works only from on-premises to cloud.  Whilst it is capable of things like password write back and device writeback, you cannot create users in Azure AD and sync them back to on-premises AD.

What you will need to do is as follows;

1). Ideally install an Exchange on-premises management server to manage attributes as the source of authority is going to be on-premises AD.  You can get a free Exchange 2016 hybrid licence key if you have Office 365 Enterprise licences for your users.

2). Setup your on-premises AD objects with the same UPN and SMTP addresses that are set in Azure AD

3).  Setup Azure AD connect to use SMTP matching and synchronise your AD to Azure AD.

You can find further information on the process below;

https://support.microsoft.com/en-gb/help/2641663/use-smtp-matching-to-match-on-premises-user-accounts-to-office-365

https://gallery.technet.microsoft.com/office/Immutableid-Hard-Match-in-d3518b08

https://docs.microsoft.com/en-gb/azure/active-directory/hybrid/how-to-connect-install-existing-tenant#hard-match-vs-soft-match

Hope this helps