The answer is to add a filter that excludes specific administrative accounts or IP ranges from the detection rule. This is the most effective way to reduce false positives in lateral movement detection because legitimate administrative activity—such as remote administration via SMB—often mirrors the exact behavior a malicious lateral movement rule is trying to catch. By explicitly whitelisting known admin accounts or trusted IP subnets, you prevent those benign events from triggering alerts while still capturing unauthorized SMB-based movement. On the MS-102 exam, this scenario tests your ability to tune custom detection rules in Microsoft Defender XDR without breaking the core detection logic; a common trap is to widen the time window or remove the join, both of which either increase noise or destroy the correlation between SMB and PowerShell that defines lateral movement. Remember the memory tip: “Whitelist the admins, not the window.”
MS-102 Practice Question: Manage security and threats by using Microsoft Defender XDR
This MS-102 practice question tests your understanding of manage security and threats by using microsoft defender xdr. 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.
```json
{
"displayName": "Custom Detection - Lateral Movement via SMB",
"queryText": "DeviceNetworkEvents | where RemotePort == 445 and ActionType == 'ConnectionSuccess' | join kind=inner (DeviceProcessEvents | where FileName == 'powershell.exe') on DeviceId | project Timestamp, DeviceName, AccountName, RemoteIP"
}
```
You create a custom detection rule in Microsoft Defender XDR using the KQL query shown in the exhibit. The rule is intended to detect lateral movement via SMB. After deploying the rule, you notice that it generates many false positives from legitimate administrative activity. What is the most effective way to reduce false positives?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a filter to exclude specific administrative accounts or IP ranges
Option D is correct because adding a filter to exclude known administrative accounts or devices can reduce false positives. Option A is wrong because increasing the time window would include more events, potentially increasing false positives. Option B is wrong because removing the join would eliminate the correlation between SMB connections and PowerShell, which is key to detecting lateral movement. Option C is wrong because focusing only on inbound connections may miss the lateral movement scenario.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Filter for only inbound SMB connections
Why it's wrong here
Lateral movement often uses outbound connections.
✗
Remove the join with DeviceProcessEvents
Why it's wrong here
This would remove the correlation that defines lateral movement.
✓
Add a filter to exclude specific administrative accounts or IP ranges
Why this is correct
Excluding known good activity reduces false positives.
Related concept
Static NAT maps one inside address to one outside address.
✗
Increase the time window of the query
Why it's wrong here
This would likely increase false positives.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MS-102 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related MS-102 NAT questions on configuration and troubleshooting.
Manage security and threats by using Microsoft Defender XDR — This question tests Manage security and threats by using Microsoft Defender XDR — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Add a filter to exclude specific administrative accounts or IP ranges — Option D is correct because adding a filter to exclude known administrative accounts or devices can reduce false positives. Option A is wrong because increasing the time window would include more events, potentially increasing false positives. Option B is wrong because removing the join would eliminate the correlation between SMB connections and PowerShell, which is key to detecting lateral movement. Option C is wrong because focusing only on inbound connections may miss the lateral movement scenario.
What should I do if I get this MS-102 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related MS-102 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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