The answer is custom detection rules in Microsoft 365 Defender. This is the correct tool because it allows security teams to define behavior-based detection logic using Kusto Query Language (KQL) within the Advanced hunting section, running those queries on a scheduled basis to generate alerts for threats not covered by built-in detections. On the Microsoft Cybersecurity Architect exam, this concept tests your ability to distinguish between built-in detection capabilities and the need for custom threat hunting—a common trap is confusing custom detection rules with automated investigation rules or attack simulation training, which serve different purposes. Remember that if the scenario explicitly states the behavior is not covered by existing detections, you must look for the custom detection feature tied to Advanced hunting. A useful memory tip is to think of KQL as the key: if you need to write a query to catch a specific pattern, you are building a custom detection rule.
SC-100 Practice Question: Evaluate GRC and security operations strategies
This SC-100 practice question tests your understanding of evaluate grc and security operations strategies. 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 Defender to protect their endpoints, email, and identities. They want to create a custom detection for a specific behavior that is not covered by built-in detections. Which tool should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Custom detection rules in Microsoft 365 Defender
Microsoft 365 Defender provides a 'Custom detection' feature under the 'Advanced hunting' section that allows security teams to create custom detection rules based on Kusto Query Language (KQL) queries. This is the correct tool because the question specifies creating a detection for behavior not covered by built-in detections within the Microsoft 365 Defender ecosystem, and custom detection rules are designed exactly for that purpose—they run on a schedule and generate alerts when the custom query matches.
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.
✗
Microsoft Sentinel analytics rules
Why it's wrong here
Sentinel is separate; custom detections in M365 Defender are native.
✗
Azure AD Identity Protection user risk policies
Why it's wrong here
Only covers identity risk, not endpoint behavior.
✓
Custom detection rules in Microsoft 365 Defender
Why this is correct
Allows creation of custom KQL queries across data sources within M365 Defender.
Related concept
Read the scenario before looking for a memorised answer.
✗
Microsoft Defender for Cloud Apps policies
Why it's wrong here
Only covers cloud apps, not endpoints or email.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Microsoft Sentinel analytics rules with Microsoft 365 Defender custom detection rules because both use KQL and create alerts, but Sentinel is a separate SIEM product, while the question explicitly asks for a tool within Microsoft 365 Defender.
Detailed technical explanation
How to think about this question
Custom detection rules in Microsoft 365 Defender leverage the same Advanced hunting schema (e.g., DeviceProcessEvents, EmailEvents, IdentityLogonEvents) and allow you to set custom alert titles, severity, and MITRE ATT&CK mapping. Under the hood, these rules are executed as scheduled queries against the Defender data store, and they can also trigger automated response actions (e.g., isolate device, block file) via the 'Actions' tab. A subtle behavior is that custom detection rules have a maximum query time window of 30 days and can only run up to every 24 hours, which is important for real-time detection planning.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-100 question in full detail.
Evaluate GRC and security operations strategies — This question tests Evaluate GRC and security operations strategies — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Custom detection rules in Microsoft 365 Defender — Microsoft 365 Defender provides a 'Custom detection' feature under the 'Advanced hunting' section that allows security teams to create custom detection rules based on Kusto Query Language (KQL) queries. This is the correct tool because the question specifies creating a detection for behavior not covered by built-in detections within the Microsoft 365 Defender ecosystem, and custom detection rules are designed exactly for that purpose—they run on a schedule and generate alerts when the custom query matches.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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