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O365 Tenant to Tenant Migration with Multi AD Forest

Chandra Sekhar 6 Reputation points
2020-09-14T19:44:16.227+00:00

Hi,

I have two O365 Tenants having their own AD Forest(A.com and B.Com) and due to recent merger, Organization A Acquired Organization B and there is forest trust between both organization. There is a Plan to Move to Organization B Users to Organization A O365 Tenant. Both A and B Organizations have their own AAD connects . However below are the concern point which i had ,

1) After Migrating the user from One O365 Tenant to Another Tenant(A.com), the authentication should take place on B.com AD .

2) If the user has to authenticate with B.Com AD, what would be the best way to do so? In this Scenario AD Migration is not considered and planning to use respective AD Forest.

Considering the above what would be the best way to migrate the user and ensuring authentication takes place with B.Com AD.

we can move the users between the tenants but the user authentication will be happen on B.Com On-Premise Active Directory. In this case once we move the user from B.Com O365 tenant to A.com O365 tenant how the user can be authenticated with B.Com AD forest? Once we move all users from B.com to A.com we will detach the domain name and will be attaching to A.com ,

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  1. Joyce Shen - MSFT 16,701 Reputation points
    2020-09-15T03:42:56.087+00:00

    Hi @Chandra Sekhar , according to your information above, you want to keep the two AD forests and move mailboxes from tenant B to tenant A, if I have any misunderstanding, please correct me.

    If so, your requirement can be achieved. The official document list the supported topology like yours: Multiple forests, single Azure AD tenant

    In tenant B, if your mailboxes located in cloud and have AD accounts, you will need to move back mailboxes from online to on-premise, and then remove your hybrid configuration from your Exchange server. This will make your organization B an on-premise only environment.

    Then you can add forest B to the existing hybrid environment. You could refer to this link to get more information about Exchange Multi-Forest Hybrid Tips and Tricks

    If an Answer is helpful, please click "Accept Answer" and upvote it.

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