- A
The domain was not verified with a TXT record.
Why wrong: The domain status shows 'Active', which means verification was completed. Verification requires a TXT record, but that only proves ownership; it does not affect email delivery.
- B
The MX record for the domain is missing or points to an incorrect mail server.
The MX record directs email to the correct mail server. If it is missing or incorrectly configured, external email will not reach Exchange Online mailboxes.
- C
The SPF record for the domain is missing or incorrectly configured.
Why wrong: SPF helps prevent spoofing but does not affect the ability to receive email. SPF is for outbound mail authentication.
- D
The custom domain was not added to the user's primary email address.
Why wrong: User email addresses can be set to the custom domain after it is verified. However, this setting affects sending, not receiving. The root cause is DNS for inbound mail.
MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
This MS-102 practice question tests your understanding of deploy and manage a microsoft 365 tenant. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company recently added the custom domain 'contoso.com' to their Microsoft 365 tenant. Users report that they cannot receive external email sent to their new domain addresses. The administrator confirmed that the domain status shows 'Active' in the Microsoft 365 admin center. What is the most likely cause of this issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The MX record for the domain is missing or points to an incorrect mail server.
The domain status 'Active' in the Microsoft 365 admin center indicates that the domain has been successfully verified and added to the tenant. However, for external email to be delivered to users at that domain, the public MX record in DNS must point to Microsoft 365's mail servers (e.g., contoso-com.mail.protection.outlook.com). If the MX record is missing or points to an incorrect server, external senders cannot route email to the tenant, even though the domain is verified and active.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The domain was not verified with a TXT record.
Why it's wrong here
The domain status shows 'Active', which means verification was completed. Verification requires a TXT record, but that only proves ownership; it does not affect email delivery.
- ✓
The MX record for the domain is missing or points to an incorrect mail server.
Why this is correct
The MX record directs email to the correct mail server. If it is missing or incorrectly configured, external email will not reach Exchange Online mailboxes.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The SPF record for the domain is missing or incorrectly configured.
Why it's wrong here
SPF helps prevent spoofing but does not affect the ability to receive email. SPF is for outbound mail authentication.
- ✗
The custom domain was not added to the user's primary email address.
Why it's wrong here
User email addresses can be set to the custom domain after it is verified. However, this setting affects sending, not receiving. The root cause is DNS for inbound mail.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see 'Active' domain status and assume all DNS configurations are correct, but Microsoft 365 separates domain verification (TXT record) from mail routing (MX record), so a verified domain can be 'Active' yet still unreachable for inbound email if the MX record is misconfigured.
Trap categories for this question
Command / output trap
The domain status shows 'Active', which means verification was completed. Verification requires a TXT record, but that only proves ownership; it does not affect email delivery.
Detailed technical explanation
How to think about this question
Under the hood, email delivery relies on the SMTP protocol, where the sending MTA performs an MX lookup for the recipient's domain. Microsoft 365 requires a specific MX record with a priority value (typically 0) pointing to the tenant's unique mail exchanger hostname (e.g., contoso-com.mail.protection.outlook.com). A common subtlety is that the MX record must be exactly as provided in the Microsoft 365 admin center, including the hyphenated domain format, and any typo or missing record will cause a 'No MX record' or 'Mail server not found' error on the sender side. In a real-world scenario, administrators often mistakenly leave the old MX record pointing to a previous on-premises server or a third-party spam filter, causing a split-routing issue where verified domains still fail to receive mail.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this MS-102 question test?
Deploy and manage a Microsoft 365 tenant — This question tests Deploy and manage a Microsoft 365 tenant — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The MX record for the domain is missing or points to an incorrect mail server. — The domain status 'Active' in the Microsoft 365 admin center indicates that the domain has been successfully verified and added to the tenant. However, for external email to be delivered to users at that domain, the public MX record in DNS must point to Microsoft 365's mail servers (e.g., contoso-com.mail.protection.outlook.com). If the MX record is missing or points to an incorrect server, external senders cannot route email to the tenant, even though the domain is verified and active.
What should I do if I get this MS-102 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
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.
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