- A
Enable Azure AD MFA with phone call for all users. Use Conditional Access to block legacy authentication. Use Identity Protection to detect risks and require MFA again.
Why wrong: Phone call MFA is not phishing-resistant.
- B
Enable Azure AD MFA with the Microsoft Authenticator app (OATH TOTP). Use Conditional Access to block legacy authentication and require MFA. Configure Identity Protection to alert on risky sign-ins.
Why wrong: Authenticator app OATH TOTP is not phishing-resistant; it can be intercepted.
- C
Deploy FIDO2 security keys to all users. Configure Conditional Access to block legacy authentication. Use Identity Protection to detect risks and send alerts to the SOC.
Why wrong: FIDO2 is phishing-resistant but hardware deployment is costly and not mentioned; also automatic remediation is not addressed.
- D
Deploy Windows Hello for Business for all users. Configure Conditional Access policies to block legacy authentication and require MFA for all cloud apps. Use Entra ID Protection to detect risky sign-ins and automatically require password change or block access.
Windows Hello for Business is phishing-resistant; Conditional Access blocks legacy auth and enforces MFA; Identity Protection handles risk detection and remediation.
Quick Answer
The answer is to deploy Windows Hello for Business for all users, configure Conditional Access policies to block legacy authentication and require MFA for all cloud apps, and use Entra ID Protection to detect risky sign-ins with automatic remediation. This solution is correct because Windows Hello for Business is a phishing-resistant MFA method that uses biometric or PIN-based authentication bound to the device, making it immune to credential theft and replay attacks—directly addressing the password spray attack vector. On the Microsoft Cybersecurity Architect exam, this scenario tests your ability to distinguish between phishing-resistant and non-phishing-resistant MFA methods under Zero Trust mandates; a common trap is choosing the Microsoft Authenticator app (OATH TOTP), which is vulnerable to MFA fatigue and not considered phishing-resistant. Remember that phishing-resistant MFA requires cryptographic proof of possession, not just a shared secret—think "something you are or have, not something you type." Memory tip: WHfB = "We Hate phishing, Biometric."
SC-100 Design security solutions for infrastructure Practice Question
This SC-100 practice question tests your understanding of design security solutions for infrastructure. 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.
You are a security architect for a large financial services company. The company has a hybrid identity infrastructure with on-premises Active Directory and Microsoft Entra ID (Azure AD). They have recently suffered a password spray attack that compromised several accounts. Management wants to implement a Zero Trust security model and has mandated the following requirements: 1. All user authentication must be protected by phishing-resistant MFA. 2. Legacy authentication protocols must be blocked. 3. All sign-in risks must be detected and automatically remediated. The current environment includes: - Microsoft 365 E5 licenses for all users. - Microsoft Entra ID P2 licenses. - On-premises Active Directory with password hash sync. - Azure AD Application Proxy for publishing on-premises apps. - A third-party VPN solution for remote access. You need to design a solution that meets the requirements. What should you do?
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
Deploy Windows Hello for Business for all users. Configure Conditional Access policies to block legacy authentication and require MFA for all cloud apps. Use Entra ID Protection to detect risky sign-ins and automatically require password change or block access.
Option A is correct because Windows Hello for Business is a phishing-resistant MFA method. Entra ID Conditional Access can block legacy authentication and enforce risk-based policies. Entra ID Protection detects sign-in risks and can automatically block or require password change. Option B is wrong because the Authenticator app (OATH TOTP) is not phishing-resistant (vulnerable to MFA fatigue). Option C is wrong because FIDO2 security keys are phishing-resistant but they are hardware tokens, not the recommended for all users; also the scenario doesn't mention hardware deployment. Option D is wrong because Azure AD MFA with phone call is not phishing-resistant.
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.
- ✗
Enable Azure AD MFA with phone call for all users. Use Conditional Access to block legacy authentication. Use Identity Protection to detect risks and require MFA again.
Why it's wrong here
Phone call MFA is not phishing-resistant.
- ✗
Enable Azure AD MFA with the Microsoft Authenticator app (OATH TOTP). Use Conditional Access to block legacy authentication and require MFA. Configure Identity Protection to alert on risky sign-ins.
Why it's wrong here
Authenticator app OATH TOTP is not phishing-resistant; it can be intercepted.
- ✗
Deploy FIDO2 security keys to all users. Configure Conditional Access to block legacy authentication. Use Identity Protection to detect risks and send alerts to the SOC.
Why it's wrong here
FIDO2 is phishing-resistant but hardware deployment is costly and not mentioned; also automatic remediation is not addressed.
- ✓
Deploy Windows Hello for Business for all users. Configure Conditional Access policies to block legacy authentication and require MFA for all cloud apps. Use Entra ID Protection to detect risky sign-ins and automatically require password change or block access.
Why this is correct
Windows Hello for Business is phishing-resistant; Conditional Access blocks legacy auth and enforces MFA; Identity Protection handles risk detection and remediation.
Related concept
Read the scenario before looking for a memorised answer.
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 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 SC-100 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.
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FAQ
Questions learners often ask
What does this SC-100 question test?
Design security solutions for infrastructure — This question tests Design security solutions for infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deploy Windows Hello for Business for all users. Configure Conditional Access policies to block legacy authentication and require MFA for all cloud apps. Use Entra ID Protection to detect risky sign-ins and automatically require password change or block access. — Option A is correct because Windows Hello for Business is a phishing-resistant MFA method. Entra ID Conditional Access can block legacy authentication and enforce risk-based policies. Entra ID Protection detects sign-in risks and can automatically block or require password change. Option B is wrong because the Authenticator app (OATH TOTP) is not phishing-resistant (vulnerable to MFA fatigue). Option C is wrong because FIDO2 security keys are phishing-resistant but they are hardware tokens, not the recommended for all users; also the scenario doesn't mention hardware deployment. Option D is wrong because Azure AD MFA with phone call is not phishing-resistant.
What should I do if I get this SC-100 question wrong?
Identify which SC-100 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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Last reviewed: Jun 21, 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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