The answer is the `ipv4_is_in_range()` KQL function, which directly compares a sign-in IP address against a specified CIDR range like `192.168.0.0/16` and returns a boolean result. This function is correct because it natively handles subnet mask calculations, allowing you to efficiently check whether the `SigninIP` field falls within the company’s approved range without needing to manually parse octets or perform bitwise operations. On the SC-200 exam, this scenario tests your ability to build custom detection rules in Microsoft 365 Defender using Advanced Hunting, specifically for alerting on sign-ins from IP addresses outside a trusted boundary. A common trap is confusing `ipv4_is_in_range()` with `ipv4_is_private()` or `ipv4_is_match()`—remember that `_in_range` is for a custom CIDR, not just private or public classification. For a memory tip, think “range check equals range function”: when you need to verify an IP against a specific allowed subnet, always reach for `ipv4_is_in_range()`.
SC-200 Mitigate threats using Microsoft Defender XDR Practice Question
This SC-200 practice question tests your understanding of mitigate threats using microsoft defender xdr. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 security analyst is creating a custom detection rule in Microsoft 365 Defender using Advanced Hunting. The rule should alert when a user signs in from an IP address that is not in the company's approved IP range (192.168.0.0/16). Which KQL function should be used to compare the sign-in IP against the approved range?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ipv4_is_in_range(SigninIP, '192.168.0.0/16')
The correct KQL function is `ipv4_is_in_range()` because it is specifically designed to check whether an IPv4 address falls within a given CIDR range. In this scenario, the function compares the `SigninIP` field against the company's approved range `192.168.0.0/16` and returns `true` if the IP is within that range, enabling the rule to alert on out-of-range sign-ins. This function handles subnet mask calculations natively, ensuring accurate and efficient IP range matching without manual parsing.
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.
✓
ipv4_is_in_range(SigninIP, '192.168.0.0/16')
Why this is correct
Correct. This function directly checks if the IP is within the given CIDR range.
Related concept
Read the scenario before looking for a memorised answer.
✗
has_any(SigninIP, dynamic(['192.168.0.0/16']))
Why it's wrong here
has_any is for substring matching, not for CIDR range evaluation.
✗
ipv4_is_private(SigninIP)
Why it's wrong here
This checks if the IP is in any private range (RFC1918), not against a specific range.
✗
SigninIP startswith '192.168.'
Why it's wrong here
String prefix matching works only for /16 ranges and fails for subnets like /24.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may choose `ipv4_is_private()` thinking it covers all internal ranges, but it does not account for custom or non-RFC 1918 ranges, and it misses the requirement to match a specific CIDR block like 192.168.0.0/16.
Detailed technical explanation
How to think about this question
The `ipv4_is_in_range()` function uses bitwise operations to compare the network prefix of the IP address against the CIDR mask, ensuring that only addresses within the exact subnet are matched. For example, `ipv4_is_in_range('192.168.1.100', '192.168.0.0/16')` returns `true` because the first 16 bits match, while `ipv4_is_in_range('192.169.1.100', '192.168.0.0/16')` returns `false`. In real-world scenarios, this function is critical for detecting anomalous sign-ins from external IPs that might fall outside a corporate VPN or trusted network range, and it supports both IPv4 and IPv6 (via `ipv6_is_in_range()`).
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-200 question in full detail.
Mitigate threats using Microsoft Defender XDR — This question tests Mitigate threats using Microsoft Defender XDR — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ipv4_is_in_range(SigninIP, '192.168.0.0/16') — The correct KQL function is `ipv4_is_in_range()` because it is specifically designed to check whether an IPv4 address falls within a given CIDR range. In this scenario, the function compares the `SigninIP` field against the company's approved range `192.168.0.0/16` and returns `true` if the IP is within that range, enabling the rule to alert on out-of-range sign-ins. This function handles subnet mask calculations natively, ensuring accurate and efficient IP range matching without manual parsing.
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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