Plan and implement a hybrid configuration and migration
Domain 3 - Plan and implement a hybrid configuration and migration
This domain tests coexistence between on-premises Exchange and Exchange Online: the Hybrid Configuration Wizard (HCW), free/busy, OAuth, migration endpoints, batches, and cutover versus staged versus hybrid migration.
Core rules
- The HCW configures hybrid connectors, accepted domains, OAuth, and organization relationships. Classic full hybrid publishes Exchange Web Services and requires certificates; modern hybrid uses the Hybrid Agent and avoids inbound publishing for migration and free/busy.
- Directory synchronization must match users by primary SMTP address or another anchor. Azure AD Connect is typical; without matching, mailboxes duplicate or migration fails.
- Migration endpoints define how the service connects to the source: Exchange Web Services, IMAP, or a public folder endpoint. MRS Proxy must be enabled on the on-premises server for remote moves.
- Cutover migration moves all mailboxes at once and suits small organizations without long coexistence. Staged migration is for Exchange 2003/2007. Hybrid migration supports long-term coexistence and online mailbox moves.
Worked example
A company has 800 Exchange 2016 mailboxes, wants shared free/busy and the ability to move mailboxes in batches while keeping some on-premises. Run the HCW in full hybrid mode, configure OAuth and the organization relationship, enable MRS Proxy on the Client Access server, create a migration endpoint, then create a migration batch with a CSV. Reasoning: hybrid preserves coexistence and free/busy; cutover would not support long-term split placement. Verify the endpoint and MRS Proxy before starting the batch; check migration reports for bad items.
Traps
- Rerunning the HCW without need can overwrite customized connectors.
- A migration endpoint that cannot reach EWS fails before any mailbox moves.
- SMTP matching failures create duplicate mail-enabled users.