Quick Answer
The answer is a third-party antivirus being installed and active, because Microsoft Defender automatically disables its real-time protection service when it detects another active antivirus product to prevent system conflicts and performance degradation. This behavior is by design in Windows 10 and Windows 11, as Defender enters a passive or disabled state when a third-party security solution is present, which is why the security console reports the service as not running even though the device is online and compliant. On the MD-102 exam, this scenario tests your understanding of Defender’s coexistence logic and how Intune-managed endpoints handle security software conflicts—a common trap is assuming compliance policy or tamper protection caused the failure, but neither disables the core service. Remember the memory tip: “One antivirus rules, the other steps aside”—if you see Defender offline, always check for a competing antivirus first.
This MD-102 practice question tests your understanding of manage applications. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 deploys Microsoft Defender for Endpoint (now Microsoft Defender XDR) on Windows 10 devices using Intune. After deployment, some devices show 'Defender service is not running' in the security console. The devices are online and compliant. 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.
Tamper protection is enabled and blocking the service.
Why wrong: Tamper protection prevents disabling, not service failure.
The devices are not compliant with the Defender policy.
Why wrong: Non-compliance would prevent configuration, not stop service.
Windows Firewall is blocking Defender updates.
Why wrong: Firewall does not affect service state.
A third-party antivirus is installed and active.
Defender disables when another AV is active.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A third-party antivirus is installed and active.
Option C is correct because if another antivirus product is active, Defender will disable itself to avoid conflict. Option A is wrong because compliance policy does not disable service. Option B is wrong because tamper protection prevents changes, not failure. Option D is wrong because firewall is unrelated.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Tamper protection is enabled and blocking the service.
Why it's wrong here
Tamper protection prevents disabling, not service failure.
The devices are not compliant with the Defender policy.
Why it's wrong here
Non-compliance would prevent configuration, not stop service.
Windows Firewall is blocking Defender updates.
Why it's wrong here
Firewall does not affect service state.
A third-party antivirus is installed and active.
Why this is correct
Defender disables when another AV is active.
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.
Common exam traps
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
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
Identify which MD-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 applications — study guide chapter
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FAQ
Manage applications — This question tests Manage applications — Read the scenario before looking for a memorised answer..
The correct answer is: A third-party antivirus is installed and active. — Option C is correct because if another antivirus product is active, Defender will disable itself to avoid conflict. Option A is wrong because compliance policy does not disable service. Option B is wrong because tamper protection prevents changes, not failure. Option D is wrong because firewall is unrelated.
Identify which MD-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.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 21, 2026
This MD-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 MD-102 exam.
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