- A
Onboard the VMs to Azure Arc and enable the Azure Update Manager on all VMs via Arc.
Why wrong: Arc is for on-premises or multi-cloud VMs; these VMs are already in Azure.
- B
Implement Azure Policy to enforce that all VMs have the 'Deploy default Microsoft IaaS anti-malware extension for Windows' policy assigned and create a remediation task.
Why wrong: The policy extension is already supposed to be deployed, but the root cause is network connectivity, not policy assignment.
- C
Configure Microsoft Entra Privileged Identity Management (PIM) to require approval for update deployments.
Why wrong: PIM is for managing privileged access, not for update deployment or connectivity.
- D
Review the network security groups (NSGs) and firewall rules to ensure outbound connectivity to the required Microsoft endpoints for Microsoft Defender for Endpoint and Windows Update.
Network connectivity is required for VMs to receive updates and communicate with Defender for Endpoint.
Quick Answer
The answer is to review the network security groups (NSGs) and firewall rules to ensure outbound connectivity to the required Microsoft endpoints for Microsoft Defender for Endpoint and Windows Update. This is correct because the symptoms—Azure VM missing updates, a Defender connectivity issue, and VMs not reporting security status—all stem from blocked outbound traffic to critical endpoints like *.endpoint.microsoft.com and *.update.microsoft.com. Without this connectivity, VMs cannot download patches, send telemetry to Defender for Cloud, or update Defender definitions, directly causing the malware outbreak on unprotected Windows VMs. On the Microsoft Cybersecurity Architect exam, this scenario tests your ability to diagnose systemic failures by linking multiple symptoms to a single root cause, often hidden in network layer misconfigurations rather than policy errors. A common trap is focusing on update schedules or Defender settings when the real issue is a missing outbound rule. Memory tip: "No route, no root" — if updates and reporting both fail, check the network path first.
SC-100 Design security for infrastructure Practice Question
This SC-100 practice question tests your understanding of design security for infrastructure. 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, Contoso Ltd., is migrating its on-premises workloads to Azure. The environment includes 200 virtual machines (VMs) running Windows Server and 50 VMs running Linux. You are responsible for designing the security infrastructure. The company has the following requirements: 1) All VMs must be protected against malware. 2) Security updates must be applied automatically to Windows VMs within 24 hours of release. 3) Linux VMs must receive critical security patches within 48 hours. 4) A central dashboard must provide visibility into the security posture of all VMs. 5) All VMs must be onboarded to Microsoft Defender for Cloud to enable advanced threat protection. 6) The solution must minimize administrative overhead. You have implemented the following: - All VMs are enrolled in Microsoft Defender for Cloud with the enhanced security features enabled. - Azure Update Manager is configured to schedule updates. - Microsoft Defender for Endpoint is installed on all Windows VMs. However, after a month, the security team reports that: - 50 Windows VMs did not receive security updates within 24 hours. - 10 Linux VMs have not received any patches. - The central dashboard shows that 30 VMs are not reporting their security status. - A malware outbreak occurred on 5 Windows VMs that were not protected by Defender for Endpoint. You need to identify the most likely root cause and recommend a corrective action.
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.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
Review the network security groups (NSGs) and firewall rules to ensure outbound connectivity to the required Microsoft endpoints for Microsoft Defender for Endpoint and Windows Update.
The correct answer is D because the symptoms—VMs missing updates, not reporting status, and lacking Defender for Endpoint protection—point to a connectivity failure. Microsoft Defender for Endpoint and Windows Update require outbound connectivity to specific Microsoft endpoints (e.g., *.endpoint.microsoft.com, *.update.microsoft.com). Without this, VMs cannot receive updates, report security posture, or download Defender definitions, directly explaining all reported issues.
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.
- ✗
Onboard the VMs to Azure Arc and enable the Azure Update Manager on all VMs via Arc.
Why it's wrong here
Arc is for on-premises or multi-cloud VMs; these VMs are already in Azure.
- ✗
Implement Azure Policy to enforce that all VMs have the 'Deploy default Microsoft IaaS anti-malware extension for Windows' policy assigned and create a remediation task.
Why it's wrong here
The policy extension is already supposed to be deployed, but the root cause is network connectivity, not policy assignment.
- ✗
Configure Microsoft Entra Privileged Identity Management (PIM) to require approval for update deployments.
Why it's wrong here
PIM is for managing privileged access, not for update deployment or connectivity.
- ✓
Review the network security groups (NSGs) and firewall rules to ensure outbound connectivity to the required Microsoft endpoints for Microsoft Defender for Endpoint and Windows Update.
Why this is correct
Network connectivity is required for VMs to receive updates and communicate with Defender for Endpoint.
Clue confirmation
The clue words "most likely", "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on configuration or policy gaps (like missing extensions or update schedules) instead of recognizing that all symptoms—missing updates, no reporting, and unprotected VMs—stem from a single underlying network connectivity issue.
Detailed technical explanation
How to think about this question
Microsoft Defender for Endpoint relies on cloud-based services for definition updates and telemetry reporting, requiring outbound HTTPS (TCP 443) to endpoints like *.endpoint.microsoft.com and *.events.data.microsoft.com. Similarly, Windows Update and Azure Update Manager depend on connectivity to *.update.microsoft.com and *.download.microsoft.com. Network security groups (NSGs) or firewalls blocking these endpoints cause VMs to fail update compliance, stop reporting to Defender for Cloud, and prevent Defender for Endpoint from functioning, leading to malware outbreaks.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 SC-100 question test?
Design security for infrastructure — This question tests Design security for infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Review the network security groups (NSGs) and firewall rules to ensure outbound connectivity to the required Microsoft endpoints for Microsoft Defender for Endpoint and Windows Update. — The correct answer is D because the symptoms—VMs missing updates, not reporting status, and lacking Defender for Endpoint protection—point to a connectivity failure. Microsoft Defender for Endpoint and Windows Update require outbound connectivity to specific Microsoft endpoints (e.g., *.endpoint.microsoft.com, *.update.microsoft.com). Without this, VMs cannot receive updates, report security posture, or download Defender definitions, directly explaining all reported issues.
What should I do if I get this SC-100 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", "minimum / minimize". 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.
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Last reviewed: Jun 11, 2026
This SC-100 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 SC-100 exam.
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