The answer is to detect brute-force attacks against Windows servers. This KQL query specifically filters Windows Security Event ID 4625, which logs every failed logon attempt, then aggregates those failures by user account, computer, and source IP address over the last hour, and finally uses a `where` clause to display only combinations exceeding 10 failures. A sudden spike of failed logins from a single IP against multiple accounts or a single account from multiple IPs is the classic signature of a brute-force attack, making this query a direct and effective detection mechanism. On the Microsoft Cybersecurity Architect exam, this scenario tests your ability to interpret KQL for threat detection in Microsoft Sentinel, often appearing in a multiple-choice format where distractors might suggest it detects password spraying, account enumeration, or denial-of-service. The key trap is confusing EventID 4625 (failed logon) with 4624 (successful logon) or 4776 (credential validation). Memory tip: think "4625 = 5 failed attempts" as a mnemonic, and remember that brute-force detection always hinges on volume—more than 10 failures in an hour is your red flag.
SC-100 Design security solutions for infrastructure Practice Question
This SC-100 practice question tests your understanding of design security solutions for infrastructure. 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.
Exhibit
Refer to the exhibit.
```kql
SecurityEvent
| where TimeGenerated > ago(1h)
| where EventID == 4625
| where AccountType == "User"
| summarize Count = count() by Account, Computer, IpAddress
| where Count > 10
| project Account, Computer, IpAddress, Count
```
Refer to the exhibit. A security analyst runs the following KQL query in Microsoft Sentinel. What is the purpose of this query?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Detect brute-force attacks against Windows servers
The query filters Windows Security Events for failed logon attempts (EventID 4625) in the last hour, groups by user account, computer, and IP address, and then shows only those with more than 10 failures. This is used to detect brute-force attacks.
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.
✗
List all accounts that have been locked out
Why it's wrong here
Incorrect: Account lockout events use different EventIDs (e.g., 4740).
✗
Identify successful logins from multiple IP addresses
Why it's wrong here
Incorrect: EventID 4625 is for failed logons.
✓
Detect brute-force attacks against Windows servers
Why this is correct
Correct: The query identifies multiple failed logon attempts from the same IP.
Related concept
Read the scenario before looking for a memorised answer.
✗
Find users who logged in after hours
Why it's wrong here
Incorrect: The query uses failed logon events, not successful logins.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-100 question in full detail.
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.
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: Detect brute-force attacks against Windows servers — The query filters Windows Security Events for failed logon attempts (EventID 4625) in the last hour, groups by user account, computer, and IP address, and then shows only those with more than 10 failures. This is used to detect brute-force attacks.
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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Question Discussion
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