- A
where InitiatingProcessAccountName !contains "SYSTEM"
Why wrong: This excludes any account that has 'SYSTEM' anywhere in the name, potentially excluding legitimate system accounts unrelated to SYSTEM.
- B
where InitiatingProcessAccountName !startswith "NT AUTHORITY"
Why wrong: This removes all NT AUTHORITY accounts (e.g., LOCAL SERVICE, NETWORK SERVICE), which is too broad and may miss valid threat detections.
- C
where InitiatingProcessAccountName !has "NT AUTHORITY\SYSTEM"
This filters out records where the account name contains the exact substring 'NT AUTHORITY\SYSTEM', effectively excluding the SYSTEM account.
- D
where InitiatingProcessAccountName !matches regex "^NT AUTHORITY\\SYSTEM$"
Why wrong: While this regex works, it is complex and not the most straightforward method; a simple !has is preferred for readability.
Quick Answer
The answer is the `!has` operator used in a `where` clause, specifically `where InitiatingProcessAccountName !has "NT AUTHORITY\SYSTEM"`. This is correct because the `!has` operator performs a case-sensitive substring match, reliably excluding the exact string `NT AUTHORITY\SYSTEM` from the `InitiatingProcessAccountName` field without accidentally filtering out accounts that contain similar substrings. On the SC-200 exam, this tests your ability to reduce alert fatigue in Microsoft Sentinel analytics rules by applying precise KQL operators to exclude system accounts from DeviceProcessEvents queries. A common trap is using `!=` (not equals) which requires an exact full-string match and can fail if the field contains domain prefixes or trailing spaces, or using `!contains` which is case-insensitive and might exclude unintended accounts. For the exam, remember that `has` is for a whole token substring match—think of it as "has this exact word"—making it the safest choice when filtering known system accounts like NT AUTHORITY\SYSTEM.
SC-200 Mitigate threats using Microsoft Sentinel Practice Question
This SC-200 practice question tests your understanding of mitigate threats using microsoft sentinel. 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 SOC analyst is building a scheduled analytics rule in Microsoft Sentinel to detect PowerShell downloads from external IPs. The rule queries the DeviceProcessEvents table from Microsoft Defender for Endpoint forwarded to Sentinel. The analyst wants to reduce alert fatigue by excluding processes initiated by known system accounts (e.g., SYSTEM). Which KQL operator should the analyst use in the query?
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
where InitiatingProcessAccountName !has "NT AUTHORITY\SYSTEM"
Option C is correct because the `!has` operator performs a case-sensitive substring match, which is the most reliable way to exclude the exact string `NT AUTHORITY\SYSTEM` from the `InitiatingProcessAccountName` field. This ensures that only processes started by the SYSTEM account (as reported by Microsoft Defender for Endpoint) are filtered out, reducing alert fatigue without accidentally excluding other accounts that might contain similar substrings.
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.
- ✗
where InitiatingProcessAccountName !contains "SYSTEM"
Why it's wrong here
This excludes any account that has 'SYSTEM' anywhere in the name, potentially excluding legitimate system accounts unrelated to SYSTEM.
- ✗
where InitiatingProcessAccountName !startswith "NT AUTHORITY"
Why it's wrong here
This removes all NT AUTHORITY accounts (e.g., LOCAL SERVICE, NETWORK SERVICE), which is too broad and may miss valid threat detections.
- ✓
where InitiatingProcessAccountName !has "NT AUTHORITY\SYSTEM"
Why this is correct
This filters out records where the account name contains the exact substring 'NT AUTHORITY\SYSTEM', effectively excluding the SYSTEM account.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
where InitiatingProcessAccountName !matches regex "^NT AUTHORITY\\SYSTEM$"
Why it's wrong here
While this regex works, it is complex and not the most straightforward method; a simple !has is preferred for readability.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `!contains` (case-insensitive) with `!has` (case-sensitive) or use `!startswith` without accounting for the full account name format, leading to either over-filtering or under-filtering of the SYSTEM account.
Detailed technical explanation
How to think about this question
In Microsoft Sentinel, the `DeviceProcessEvents` table from Microsoft Defender for Endpoint stores the `InitiatingProcessAccountName` as a string that often includes the domain and account name (e.g., 'NT AUTHORITY\SYSTEM'). The `!has` operator is optimized for exact substring matching and is case-sensitive, making it ideal for filtering out known system accounts without false positives. A real-world scenario where this matters is when a SOC analyst needs to exclude SYSTEM processes but still catch malicious PowerShell downloads initiated by other accounts like 'LOCAL SERVICE' or 'NETWORK SERVICE', which would not be affected by this filter.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
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FAQ
Questions learners often ask
What does this SC-200 question test?
Mitigate threats using Microsoft Sentinel — This question tests Mitigate threats using Microsoft Sentinel — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: where InitiatingProcessAccountName !has "NT AUTHORITY\SYSTEM" — Option C is correct because the `!has` operator performs a case-sensitive substring match, which is the most reliable way to exclude the exact string `NT AUTHORITY\SYSTEM` from the `InitiatingProcessAccountName` field. This ensures that only processes started by the SYSTEM account (as reported by Microsoft Defender for Endpoint) are filtered out, reducing alert fatigue without accidentally excluding other accounts that might contain similar substrings.
What should I do if I get this SC-200 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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Last reviewed: Jun 11, 2026
This SC-200 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-200 exam.
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