The answer is that the KQL query returns no results because EventID 4625 does not capture all authentication failures, which is the most likely issue when troubleshooting a brute-force attack query. While EventID 4625 records failed logon attempts at the Windows Security log level, brute-force attacks often target protocols like RDP, SMB, or network-level authentication that generate different EventIDs such as 4648, 4776, or 5156, and some attempts may be blocked before reaching the log source. On the Microsoft Cybersecurity Architect exam, this tests your understanding of Windows security event taxonomy and the common trap of assuming a single EventID covers all failure scenarios—a key oversight in KQL query design for Sentinel detections. To remember this, think of the mnemonic "4625 is just the tip of the iceberg" and always verify which authentication protocol is being targeted before narrowing your query.
SC-100 Practice Question: Design security operations, identity, and compliance capabilities
This SC-100 practice question tests your understanding of design security operations, identity, and compliance capabilities. 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.
Exhibit
SecurityEvent
| where EventID == 4625
| summarize FailureCount = count() by Account, IPAddress
| where FailureCount > 10
| project Account, IPAddress, FailureCount
Refer to the exhibit. A KQL query is used in Microsoft Sentinel to detect brute-force attacks. The query returns no results despite known brute-force attempts. What is the most likely issue?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The EventID 4625 may not cover all authentication failures
EventID 4625 in Windows Security logs specifically records failed logon attempts, but brute-force attacks may target other authentication protocols (e.g., RDP, SMB, or network-level authentication) that generate different EventIDs (such as 4648, 4776, or 5156). Additionally, some brute-force attempts might be blocked at the network layer or use non-Windows authentication methods, so relying solely on EventID 4625 will miss those events. Therefore, the query returns no results because it does not capture all authentication failure scenarios.
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.
✓
The EventID 4625 may not cover all authentication failures
Why this is correct
Some authentication failures use other EventIDs.
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.
✗
The query lacks a time filter
Why it's wrong here
Time filter is not required for detection, though it helps.
✗
The 'IPAddress' field does not exist in SecurityEvent
Why it's wrong here
IPAddress is a valid field.
✗
The 'count()' aggregation is incorrect
Why it's wrong here
count() is valid.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Microsoft often tests the misconception that a single EventID (like 4625) covers all authentication failures, when in reality different protocols and authentication methods generate distinct EventIDs, and candidates must consider the broader log source landscape.
Detailed technical explanation
How to think about this question
Windows Security EventID 4625 is logged for logon failures at the Winlogon level, but brute-force attacks often use protocols like RDP (which may generate EventID 4625 only if the logon attempt reaches the authentication layer) or SMB (which can generate EventID 5140 or 5145). In real-world scenarios, attackers may also use password spraying against web applications or VPNs that log to different data sources (e.g., Azure AD Sign-in logs, IIS logs), so a KQL query scoped only to SecurityEvent with EventID 4625 will miss those events entirely. Understanding the mapping of authentication failures to specific EventIDs and data sources is critical for comprehensive brute-force detection.
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.
Design security operations, identity, and compliance capabilities — This question tests Design security operations, identity, and compliance capabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The EventID 4625 may not cover all authentication failures — EventID 4625 in Windows Security logs specifically records failed logon attempts, but brute-force attacks may target other authentication protocols (e.g., RDP, SMB, or network-level authentication) that generate different EventIDs (such as 4648, 4776, or 5156). Additionally, some brute-force attempts might be blocked at the network layer or use non-Windows authentication methods, so relying solely on EventID 4625 will miss those events. Therefore, the query returns no results because it does not capture all authentication failure scenarios.
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". 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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