Deploy and manage a Microsoft 365 tenant →easyMultiple ChoiceObjective-mapped

MS-102 Deploy and manage a Microsoft 365 tenant Practice Question

A company has recently signed up for Microsoft 365 Business Premium. They want to change the default domain from onmicrosoft.com to a custom domain they own. Which step must be completed first before the custom domain can be used for user email addresses?

⚠ Common exam trap

Many exam-takers confuse the order of operations, assuming DNS verification (Option B) is the first step, but Microsoft 365 requires the domain to be added to the tenant as a prerequisite before any DNS records can be validated.

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

✓

Add the custom domain in the Microsoft 365 admin center

Before a custom domain can be used for user email addresses in Microsoft 365, the domain must first be added to the tenant in the Microsoft 365 admin center. This step creates a domain object in Azure AD that allows Microsoft to associate the domain with your tenant and prepare for ownership verification. Without adding the domain first, subsequent steps like DNS verification or user creation cannot proceed because the system has no record of the domain.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
Add the custom domain in the Microsoft 365 admin center
Why this is correct
Adding the custom domain in the Microsoft 365 admin center is the mandatory first step to associate your existing DNS namespace with your tenant. From Domains > Add domain, you enter the domain name, which triggers Microsoft's verification wizard and generates the exact DNS records you must publish. Until this addition is completed, no downstream tasks like verification or user provisioning can begin.
✗
Verify domain ownership by adding a TXT record to the domain's DNS
Why it's wrong here
Verifying domain ownership with a TXT record is a secondary step that depends on an already-added domain because the wizard must generate a unique verification string for your specific domain. You cannot create or retrieve that TXT record in DNS unless the custom domain is first registered in the Microsoft 365 admin center, so performing verification beforehand is impossible. Even after verification succeeds, there are still additional tasks such as setting the domain as default and assigning users.
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Create user accounts with the new domain as their primary email
Why it's wrong here
Creating user accounts with the new domain as their primary email requires that the domain already be added and proven via ownership verification, otherwise Microsoft 365 will reject the domain suffix as unverified. User provisioning APIs and the admin center both validate the domain before allowing you to assign it to a UPN or email address. Attempting to do this before adding the domain will fail with an unverified domain error.
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Configure email exchange records (MX)
Why it's wrong here
Configuring MX records affects inbound email routing and is typically performed to make mailboxes receive mail, but it has no bearing on adding or verifying domain ownership. The domain can be added and verified without any MX record, and Microsoft 365 does not require MX configuration at initial setup. Adding MX records too early could even be counterproductive if you are not yet ready to cut over email flow from your existing provider.

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MS-102 Deploy and manage a Microsoft 365 tenant Practice Question

Why each option matters

Option-by-option breakdown

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