The most likely cause is that the Microsoft Defender for Endpoint sensor is not reporting to the service. Even when a device is powered on and connected to the network, the sensor must send regular heartbeat signals to the cloud; if these communications fail or are delayed beyond a configured threshold, the device inventory status changes to "Inactive." This scenario directly tests your understanding of sensor health monitoring in the Microsoft 365 Administrator MS-102 exam, where a common trap is assuming network connectivity alone guarantees active status. The key distinction is that the sensor uses HTTPS to report, so a firewall blocking outbound traffic to Defender endpoints can also cause inactivity, but the core issue is the sensor’s failure to communicate. Remember: a device can be "on" but "silent" — think of the sensor as the device’s voice; if it stops talking, Defender marks it inactive.
MS-102 Practice Question: Manage security and threats by using Microsoft Defender XDR
This MS-102 practice question tests your understanding of manage security and threats by using microsoft defender xdr. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
You manage Microsoft Defender for Endpoint. A device is showing as 'Inactive' in the device inventory. The device is turned on and connected to the network. What is the most likely cause?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Microsoft Defender for Endpoint sensor is not reporting
Option D is correct because the sensor needs to communicate regularly; if not, the device shows inactive. Option A is wrong because the device is on. Option B is wrong because the firewall might block, but usually the sensor communication uses HTTPS. Option C is wrong because the onboarding script is only for initial setup.
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 device is turned off
Why it's wrong here
The device is turned on as per the scenario.
✗
A firewall is blocking communication with the Microsoft Defender for Endpoint cloud service
Why it's wrong here
While possible, the most likely cause is the sensor not reporting.
✓
The Microsoft Defender for Endpoint sensor is not reporting
Why this is correct
If the sensor stops reporting, the device shows as inactive.
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 onboarding script was not run successfully
Why it's wrong here
If it were not run, the device would not appear at all.
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.
Trap categories for this question
Scenario analysis trap
The device is turned on as per the scenario.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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.
Manage security and threats by using Microsoft Defender XDR — This question tests Manage security and threats by using Microsoft Defender XDR — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Microsoft Defender for Endpoint sensor is not reporting — Option D is correct because the sensor needs to communicate regularly; if not, the device shows inactive. Option A is wrong because the device is on. Option B is wrong because the firewall might block, but usually the sensor communication uses HTTPS. Option C is wrong because the onboarding script is only for initial setup.
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.
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Your organization uses Microsoft Defender for Endpoint. A user reports that their device is not receiving security updates. You need to ensure that the device is properly onboarded to Defender for Endpoint. Which log should you check first?
medium
A.Event Viewer Application logs
B.System logs
✓ C.Microsoft Defender for Endpoint client logs
D.Windows Update logs
Why C: Option D is correct because the Microsoft Defender for Endpoint client logs (e.g., C:\ProgramData\Microsoft\Windows Defender\Platform\*\MpCmdRun.log) provide detailed information about onboarding and update issues. Option A (Event Viewer Application logs) may show some errors but not as detailed. Option B (Windows Update logs) are for Windows Update, not Defender updates. Option C (System logs) are for system events.
Last reviewed: Jun 21, 2026
Question Discussion
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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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