The correct answer is the KQL query that uses `DnsEvents | summarize count() by ClientIP, Subdomain | where count_ > 100`. This query detects DNS tunneling by identifying a single client generating an abnormally high volume of queries to many unique subdomains, which is a classic indicator of data exfiltration where attackers encode stolen data into DNS requests. On the Microsoft Security Operations Analyst SC-200 exam, this question tests your ability to distinguish between legitimate DNS traffic and covert channels; common traps include focusing on packet size or failed queries, which are less reliable for tunneling detection. Remember that DNS tunneling relies on volume and subdomain uniqueness, not payload size or error rates. A helpful memory tip is "Subdomain Surge" — if a client is flooding DNS with hundreds of unique subdomains, think tunneling.
SC-200 Perform threat hunting Practice Question
This SC-200 practice question tests your understanding of perform threat hunting. 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 threat hunter suspects a data exfiltration attempt via DNS tunneling. Which KQL query would best detect unusual DNS query patterns in Microsoft Sentinel?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
DnsEvents | summarize count() by ClientIP, Subdomain | where count_ > 100
To detect DNS tunneling, you need to look for high volume of queries to many unique domains or subdomains. Option A looks for large size (not typical for tunneling). Option B looks for failed queries. Option D is too broad. Option C (queries with many unique subdomains) is a classic sign of DNS tunneling.
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.
✓
DnsEvents | summarize count() by ClientIP, Subdomain | where count_ > 100
Why this is correct
High count of queries to the same IP with many subdomains suggests tunneling.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
DnsEvents | where ResponseSize > 1000
Why it's wrong here
DNS tunneling often uses small queries; size alone is not a good indicator.
✗
DnsEvents | where ResultCode != 0
Why it's wrong here
Non-zero result codes indicate failures, not tunneling.
✗
DnsEvents | where QueryType == 'A'
Why it's wrong here
Filtering by query type alone is not specific to tunneling.
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 SC-200 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 SC-200 NAT questions on configuration and troubleshooting.
Perform threat hunting — This question tests Perform threat hunting — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: DnsEvents | summarize count() by ClientIP, Subdomain | where count_ > 100 — To detect DNS tunneling, you need to look for high volume of queries to many unique domains or subdomains. Option A looks for large size (not typical for tunneling). Option B looks for failed queries. Option D is too broad. Option C (queries with many unique subdomains) is a classic sign of DNS tunneling.
What should I do if I get this SC-200 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 SC-200 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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