The correct answer is to verify that an SPF TXT record exists for contoso.com. This is because when external email delivery fails despite a properly configured MX record pointing to Microsoft 365, the most common culprit is a missing or incorrect SPF record, which authorizes specific mail servers to send email on behalf of your domain. Without it, receiving mail servers often reject or quarantine messages, mistaking them for spoofed or unauthorized traffic. On the MS-102 exam, this scenario tests your understanding of DNS-based mail flow authentication, a core concept for hybrid and cloud-only environments. A common trap is to assume the MX record alone guarantees inbound delivery, but SPF is a separate prerequisite for external senders. Remember the memory tip: "MX gets mail in, but SPF lets it through the door."
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.
Your organization has a Microsoft 365 tenant configured with a custom domain contoso.com. Users report they cannot receive email from external senders; internal email works fine. You verify the MX record for contoso.com points to the Microsoft 365 mail exchanger. What should you check next?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify that an SPF TXT record exists for contoso.com.
The most common cause of external email delivery failure after MX record configuration is a missing or incorrect SPF record. SPF is required to prevent spoofing and ensure delivery. Option B (Sender Policy Framework record) is correct. Option A is wrong because the MX record is already verified. Option C is wrong because DNS propagation typically completes within minutes to hours; waiting longer is not a diagnostic step. Option D is wrong because Exchange admin center settings do not affect inbound mail flow at the DNS level.
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.
✗
Check the Exchange admin center for connector configuration.
Why it's wrong here
Inbound connectors are not required for standard inbound mail flow from external senders.
✓
Verify that an SPF TXT record exists for contoso.com.
Why this is correct
External senders often reject mail if SPF is missing or misconfigured.
Related concept
Read the scenario before looking for a memorised answer.
✗
Wait 48 hours for DNS propagation.
Why it's wrong here
DNS changes typically propagate within hours; waiting is not a proactive diagnostic step.
✗
Verify that the MX record has a priority of 0.
Why it's wrong here
There is no requirement for MX priority to be 0; any valid priority works.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MS-102 question in full detail.
Identify which MS-102 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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: Verify that an SPF TXT record exists for contoso.com. — The most common cause of external email delivery failure after MX record configuration is a missing or incorrect SPF record. SPF is required to prevent spoofing and ensure delivery. Option B (Sender Policy Framework record) is correct. Option A is wrong because the MX record is already verified. Option C is wrong because DNS propagation typically completes within minutes to hours; waiting longer is not a diagnostic step. Option D is wrong because Exchange admin center settings do not affect inbound mail flow at the DNS level.
What should I do if I get this MS-102 question wrong?
Identify which MS-102 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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