MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
A company plans to migrate their email from an on-premises Exchange server to Exchange Online. They want to ensure that during the migration, mail sent to users who have already been migrated is delivered to Exchange Online, while mail for non-migrated users is delivered to on-premises. Which type of domain configuration should they use?
⚠ Common exam trap
A common mix-up: candidates confuse 'split domain' with 'hybrid deployment' or 'coexistence,' but the question specifically asks for the domain configuration type, not the overall migration method; Microsoft often tests the exact terminology for mail flow scenarios during phased migrations.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Split domain
A split domain configuration is required when some mailboxes reside on-premises and others in Exchange Online during a migration. It uses MX records pointing to Exchange Online Protection (EOP) and internal mail flow connectors to route messages for migrated users to Exchange Online and non-migrated users to on-premises, ensuring each mailbox receives mail at its current location.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Coexistence domain
Why it's wrong here
Coexistence domain is not a recognized domain type in Microsoft 365. In hybrid deployments, coexistence refers to the operational state where on-premises Exchange and Exchange Online share address space and directory synchronization, but no special domain is created. Mail routing between the two environments relies on the hybrid configuration (e.g., the Hybrid Configuration Engine) and an on-premises connector, not on a separate 'coexistence domain'. Therefore, selecting this option is incorrect because the domain itself remains a single authoritative domain with routing controlled by the hybrid setup, not a distinct domain object.
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Shared domain
Why it's wrong here
Shared domain is not a valid domain configuration in Microsoft 365. While 'shared' might imply that mailboxes for the same SMTP domain exist both on-premises and in the cloud, Microsoft's terminology for that scenario is 'split domain' or 'shared SMTP address space' (an Exchange term). There is no domain type called 'shared domain' in the Microsoft 365 admin center or in Exchange Online management, and no specific routing behavior is defined for it. Thus, this option is incorrect because it misnames the actual concept and lacks any corresponding implementation in the platform.
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Split domain
Why this is correct
Split domain (also called shared SMTP address space) is the correct configuration when a single accepted domain has mailboxes both on-premises and in Exchange Online, as in this migration scenario. In an Exchange hybrid deployment, you configure the on-premises organization and Exchange Online to recognize the same domain as authoritative, and then create a send connector and a receiving connector (or use the Hybrid Configuration Wizard) to route messages based on the mailbox location. This allows mail for recipients with the same domain suffix to be delivered correctly to either environment, which is exactly the requirement when migrating mailboxes from on-premises to the cloud.
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Forwarding domain
Why it's wrong here
A forwarding domain is not a domain type used in Microsoft 365 or Exchange for hybrid mail routing. Forwarding is a mailbox-level or transport rule feature that redirects messages from one recipient to another, such as set-command or an email forwarding rule; it does not alter the domain's routing topology. Even if you created a domain solely to forward mail, that would require an MX record pointing to a relay service and would not integrate with Exchange Online's hybrid routing logic. Hence, this option is incorrect because it confuses recipient-level redirection with a domain-level configuration that does not exist.
Go deeper
Related to this question
Learn chapter
Exchange Online Administration
Key term
Mailbox
A mailbox is a storage location on a mail server where incoming and outgoing email messages are kept for a user or group.
Key term
Exchange Online
Exchange Online is Microsoft's cloud-based email, calendar, and contact hosting service that is part of the Microsoft 365 suite, allowing organizations to manage corporate messaging without maintaining their own mail servers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MS-102 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MS-102 exam.