Exchange hybrid deployments with multiple forests

Question

Exchange hybrid deployments with multiple forests

Chiew Sheng Liew 1

Hi,

I have 2 forest with a 2 way trust that are link to the same tenant. There is on-premise Exchange setup in each forest and both require hybrid setup. I'm having some mailbox connectivity issue for one of the forest. Is there a write up that I can refer to for Exchange hybrid deployments with multiple forests?

Regards,
Chiew Sheng

3 answers

Your answer

Answer 1

@Chiew Sheng Liew

Here are supported AAD Connect Topologies: Topologies for Azure AD Connect, you need to choose the correct one based on your organization. For more detailed information about it, you can also confirm with the Azure AD Connect team.

Mark sure your AAD Connect topology is supported, then you will create hybrid with them. The way is similar to create hybrid with one forest.

Here are article from Microsoft: Hybrid deployments with multiple forests

Here are blogs which may be useful to you:

Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

Chiew Sheng Liew 1

Hi Kyle,

My client is using multiple forests, single Azure AD tenant topology. Both forest have Exchange servers installed and have exchange hybrid configured. I'm trying to setup the same configuration in my lab and is getting some abnormalities for my 2nd exchange hybrid configuration. Is there a detail guide I can reference to hybrid with multiple forest? The docs from Microsoft below is quite high level.

https://learn.microsoft.com/en-us/exchange/hybrid-deployment/hybrid-with-multiple-forests

KyleXu-MSFT 26,396 Reputation points

2021-10-01T09:16:23.937+00:00

Both forest have Exchange servers installed and have exchange hybrid configured

I have some doubts about this one. Do you mean that you have a Exchange online hybrid with two forests, but now want to create independent Exchange online for each forest, like this one below?

If so, you need to create AAD Connect for each forest, then run HCW for each forest directly.

Answer 3

Chiew Sheng Liew 1

Hi Kylie,

Not the model shown. My client is using multiple forests, single Azure AD tenant model below. Both forest have Exchange servers with hybrid installed. Any reference I can use to setup in my lab?

KyleXu-MSFT 26,396 Reputation points

2021-10-04T08:15:30.197+00:00

Do you mean the above picture is the current topology? In this topology, you can only have one Office 365. There only exist one article from Microsoft introduce about it(Provide it to you before): Configuring hybrid deployments in multi-forest organizations

There exist a article from third party blog which may also useful to you: Office 365 Hybrid Deployment with Multiple Active Directory Forests
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

If you want to create a separate Office 365 for each forest, you need to change to topology I provided.
KyleXu-MSFT 26,396 Reputation points

2021-10-07T08:57:37.647+00:00

@Chiew Sheng Liew

Any update about this thread now? Do you deploy successfully?
Liew Chiew Sheng 11 Reputation points

2021-10-11T17:21:06.627+00:00

Hi Kyle, as mention multiple forests to a single Azure AD tenant meaning one office 365. Both forest have their own Exchange servers with hybrid installed. Is this doable?
Liew Chiew Sheng 11 Reputation points

2021-10-14T06:00:13.84+00:00

Hi Kyle,

I managed to configure hybrid for each of the 2 forest within the same tenant. These 2 exchange are different exchange organization. Can I check with you if my configuration supported?

regards,
Chiew Sheng

Share via

Exchange hybrid deployments with multiple forests

3 answers

Your answer