MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
An organization has just purchased Microsoft 365 Business Standard licenses and has added the custom domain 'contoso.com' to the tenant. The administrator wants all new user email addresses to use '@contoso.com' instead of the default '@contoso.onmicrosoft.com'. How can this be achieved?
⚠ Common exam trap
Candidates often think they must manually update each user or use PowerShell because they overlook the simple default domain configuration in the admin center, which automatically applies to all new user creations.
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
✓
Set the default domain in the Microsoft 365 admin center to contoso.com
Setting the default domain to 'contoso.com' in the Microsoft 365 admin center ensures that all newly created users automatically receive an email address with the custom domain as their primary SMTP address. This is the standard method because the default domain setting controls the domain appended to new user accounts during creation, eliminating the need for manual changes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set the default domain in the Microsoft 365 admin center to contoso.com
Why this is correct
Setting contoso.com as the default domain in the Microsoft 365 admin center is the correct tenant-wide configuration. When you set a verified custom domain as the default, every new user created through the admin center automatically receives a user principal name (UPN) and email address ending with @contoso.com, without requiring any per-user steps. This setting persists for all future user creations and does not alter existing users' addresses, making it the standard way to ensure automatic assignment of the custom domain.
- ✗
Change the primary SMTP address for each user manually after creation
Why it's wrong here
Manually altering the primary SMTP address after creation does not scale to the requirement that *all new* users automatically receive the custom domain; it requires individual intervention per user, whereas the correct approach—setting the custom domain as the default in Microsoft Entra ID—applies the domain to every new mailbox without manual steps. This option is tempting because it is a valid method for correcting a single user’s address or for migrating an existing user from one domain to another, but it fails here because the stem demands a persistent, automated default for all future users.
- ✗
Remove the onmicrosoft.com domain from the tenant
Why it's wrong here
The onmicrosoft.com domain (e.g., contoso.onmicrosoft.com) is the initial cloud domain provisioned for every Microsoft 365 tenant and is reserved by Microsoft Entra ID; it cannot be removed or deleted from the tenant. Even if removal were possible, deleting it would not cause new users to be created with the custom domain—it would simply break the fallback domain used for directory services and conflict with the tenant's identity foundation. Therefore, this action is both impossible and ineffective for the stated requirement.
- ✗
Edit the user creation PowerShell script to specify the domain
Why it's wrong here
Editing a PowerShell script to specify contoso.com for each new user is an ad-hoc, per-user approach rather than a tenant configuration change. It would only work for the subset of users created via that specific script, and it would not affect users created through the Microsoft 365 admin center, Microsoft Entra admin center, or other portals. In contrast, setting the default domain is a single, persistent, tenant-wide setting that applies automatically to all new users regardless of how they are provisioned, making the script method both error-prone and insufficient for the requirement.
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Related to this question
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Microsoft 365 Tenant Setup
Key term
Microsoft 365
Microsoft 365 is a subscription-based cloud service from Microsoft that combines productivity tools like Office apps with security, device management, and online storage.
Key term
Custom domain
A custom domain is a personalized internet address (like contoso.com) that you can use with cloud services instead of the default domain provided by the service provider.
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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.