This 200-201 practice question tests your understanding of security monitoring. 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 receives an alert from the SIEM indicating a high number of outbound DNS queries from an internal host to a domain known for malicious activity. The analyst reviews the logs and finds that the host is a DNS server. What should be the analyst's first action?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Isolate the DNS server from the network and escalate to incident response.
The correct first action is to isolate the DNS server from the network and escalate to incident response. A DNS server generating outbound DNS queries to a known malicious domain indicates a likely compromise (e.g., DNS tunneling or malware command-and-control), not normal recursive resolution. Immediate containment prevents further data exfiltration or lateral movement, aligning with incident response best practices.
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.
✓
Isolate the DNS server from the network and escalate to incident response.
Why this is correct
Immediate containment to prevent further compromise.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Check the baseline of DNS traffic to confirm it is anomalous.
Why it's wrong here
Baseline check is good but not first action.
✗
Block the domain at the firewall and close the alert.
Why it's wrong here
Blocking is reactive; isolation is more critical.
✗
Restart the DNS service on the server and monitor.
Why it's wrong here
Restarting may remove evidence.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a DNS server's outbound queries are always benign recursive lookups, leading candidates to choose baseline checking or simple blocking instead of recognizing the need for immediate containment and escalation.
Detailed technical explanation
How to think about this question
DNS servers typically operate in a recursive or authoritative capacity; a recursive server queries external domains on behalf of clients, but a sudden spike to a known malicious domain (e.g., a DGA-based C2) suggests the server itself is compromised. In real-world attacks like DNS tunneling, the server may be used to exfiltrate data via TXT records or subdomain queries, making isolation critical before forensic analysis. The NIST SP 800-61 incident response framework emphasizes containment as the first priority after detection.
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 practitioner preparing for the 200-201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Monitoring — This question tests Security Monitoring — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Isolate the DNS server from the network and escalate to incident response. — The correct first action is to isolate the DNS server from the network and escalate to incident response. A DNS server generating outbound DNS queries to a known malicious domain indicates a likely compromise (e.g., DNS tunneling or malware command-and-control), not normal recursive resolution. Immediate containment prevents further data exfiltration or lateral movement, aligning with incident response best practices.
What should I do if I get this 200-201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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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