This MS-900 practice question tests your understanding of describe microsoft 365 apps and services. 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.
A company uses Microsoft 365 E5 and wants to implement a solution that automatically detects and remediates security incidents across endpoints, email, and identities. Which service should they use?
Microsoft Defender XDR
Defender XDR provides cross-domain detection and automated response.
Microsoft Purview
Why wrong: Purview is for data governance and compliance, not security incident response.
Microsoft Defender for Cloud
Why wrong: This is for cloud security posture management, not cross-domain incident response.
Microsoft Sentinel
Why wrong: Sentinel is a SIEM that requires manual or custom playbooks for response.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Microsoft Defender XDR
Microsoft Defender XDR (Extended Detection and Response) is the correct choice because it provides a unified, cross-domain security solution that automatically detects, investigates, and remediates threats across endpoints, email, and identities. It leverages AI and automation to correlate signals from Microsoft Defender for Endpoint, Defender for Office 365, and Defender for Identity, enabling coordinated incident response without manual intervention.
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.
Microsoft Defender XDR
Why this is correct
Defender XDR provides cross-domain detection and automated response.
Related concept
Read the scenario before looking for a memorised answer.
Microsoft Purview
Why it's wrong here
Purview is for data governance and compliance, not security incident response.
Microsoft Defender for Cloud
Why it's wrong here
This is for cloud security posture management, not cross-domain incident response.
Microsoft Sentinel
Why it's wrong here
Sentinel is a SIEM that requires manual or custom playbooks for response.
Common exam traps
The trap here is that candidates often confuse Microsoft Defender for Cloud (a cloud workload protection tool) with Microsoft Defender XDR, or mistakenly think Microsoft Sentinel (a SIEM) is the primary automated remediation tool, when in fact Sentinel requires custom playbooks and is not designed for cross-domain automated remediation out of the box.
Detailed technical explanation
Under the hood, Microsoft Defender XDR uses the Microsoft 365 Defender portal to unify alerts from Defender for Endpoint (using sensor-based behavioral analysis and machine learning on endpoints), Defender for Office 365 (analyzing email headers, URLs, and attachments via detonation and heuristics), and Defender for Identity (monitoring on-premises Active Directory signals via domain controller agents). The service automatically correlates these alerts into a single incident, applies automated investigation (using playbooks and AI), and can execute remediation actions such as isolating a compromised endpoint, deleting malicious emails, or disabling a compromised user account—all without requiring custom SIEM rules or manual orchestration.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Describe Microsoft 365 apps and services — This question tests Describe Microsoft 365 apps and services — Read the scenario before looking for a memorised answer..
The correct answer is: Microsoft Defender XDR — Microsoft Defender XDR (Extended Detection and Response) is the correct choice because it provides a unified, cross-domain security solution that automatically detects, investigates, and remediates threats across endpoints, email, and identities. It leverages AI and automation to correlate signals from Microsoft Defender for Endpoint, Defender for Office 365, and Defender for Identity, enabling coordinated incident response without manual intervention.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This MS-900 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-900 exam.
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