Cloud Sync with Exchange Hybrid setup first

Question

Our contractor has set up Exchange Hybrid without Entra Connect or Cloud Sync set up even though it is a prerequisite. Since this is a weird situation and my first time working with a hybrid environment I could not find the answers to a few questions I had, if anyone knows it would be very helpful.

First is if we do not set up a sync for users is there any problems we will encounter with users having both an onsite and cloud account with the same username but separate.

Second is if we do look to set up Entra Cloud Sync will there be any issues since Exchange Hybrid is already set up.

Lastly was how does Entra Cloud Sync handle Cloud accounts that already exist when you sync? I know Entra Connect will search for those and sync them with the exception of cloud administrator accounts. There however isn't a specific page for doing this with Cloud Sync and was wondering if it works the same since we already have a few regular and administrators with a cloud only account that would be getting synced.

Thank you for any insights. *Copied from another microsoft forum as I got redirected here.

Answer 1

Great to know that your question has been resolved and thanks for sharing your test results so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others", I'll repost your solution in case you'd like to "Accept" the answer : )     

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Issue Symptom: 

Set up Exchange Hybrid without Entra Connect or Cloud Sync set up even though it is a prerequisite.

•  If do not set up a sync for users is there any problems we will encounter with users having both an onsite and cloud account with the same username but separate.
• if we do look to set up Entra Cloud Sync will there be any issues since Exchange Hybrid is already set up.
• how does Entra Cloud Sync handle Cloud accounts that already exist when you sync

Resolution: 

Test result:

1. There would have been issues such as Entra ID users not being able to see AD users in the global address list without sync. All users must be synced even if they aren't licensed to have similar hybrid features work.
2. There were no issues when setting up Entra ID Cloud Sync after setting up Exchange Hybrid. Enabling Exchange Writeback worked as expected and migrating mailboxes worked.
3. Entra ID Cloud Sync handles already existing accounts almost the same way as Entra ID Connect Sync from my testing. They will sync with the existing account unless it is an admin in Entra ID. If the user is an admin in Entra ID it will create a new user. https://learn.microsoft.com/en-us/entra/identity/hybrid/connect/how-to-connect-install-existing-tenant

 

Answer 2

Hi,

Welcome to Microsoft Q&A community.

Problems with Separate Onsite and Cloud Accounts:

Without synchronization, having both an onsite and cloud account with the same username but separate can lead to several issues. Users might face difficulties with authentication and accessing resources consistently. This setup could cause user confusion, login issues, and potential conflicts in resource management.

Setting Up Entra Cloud Sync After Exchange Hybrid:

Introducing Entra Cloud Sync after setting up Exchange Hybrid should not cause significant issues. However, it’s crucial to ensure that the synchronization process is carefully planned and executed to avoid any disruptions. Proper synchronization will help unify user identities across both environments, which is essential for a seamless hybrid experience.

Handling Existing Cloud Accounts with Entra Cloud Sync:

Entra Cloud Sync can handle existing cloud-only accounts, but it works differently compared to Entra Connect. While Entra Connect searches for and syncs existing accounts (excluding cloud administrator accounts), Entra Cloud Sync also supports synchronization but may have different handling mechanisms. It’s important to review the specific documentation and settings for Entra Cloud Sync to ensure it aligns with your requirements.

For more information you can refer to :https://learn.microsoft.com/en-us/entra/identity/hybrid/exchange-hybrid-writeback

Answer 3

I did some testing myself

1. There would have been issues such as Entra ID users not being able to see AD users in the global address list without sync. All users must be synced even if they aren't licensed to have similar hybrid features work.
2. There were no issues when setting up Entra ID Cloud Sync after setting up Exchange Hybrid. Enabling Exchange Writeback worked as expected and migrating mailboxes worked.
3. Entra ID Cloud Sync handles already existing accounts almost the same way as Entra ID Connect Sync from my testing. They will sync with the existing account unless it is an admin in Entra ID. If the user is an admin in Entra ID it will create a new user. https://learn.microsoft.com/en-us/entra/identity/hybrid/connect/how-to-connect-install-existing-tenant