hardMultiple Choice
200-201 Practice Question: A Cisco Firepower appliance generates an…
A Cisco Firepower appliance generates an intrusion specific event with the message 'MALWARE-CNC generic command and control traffic detected'. The analyst needs to determine if the alert is a true positive. Which additional data source would provide the most corroborating evidence?
⚠ Common exam trap
Cisco often tests the misconception that NetFlow or URL filtering logs are sufficient for C2 detection, but the key is that DNS logs reveal the domain resolution step that is almost always part of C2 communication, making them the most direct corroborating source.
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
✓
DNS query logs
DNS query logs are the most corroborating evidence because malware command-and-control (C2) traffic often relies on DNS to resolve the IP address of the C2 server. A sudden spike in NXDOMAIN responses, queries to algorithmically generated domains (DGA), or requests to known malicious domains in the DNS logs would directly confirm the C2 activity. This aligns with the 'MALWARE-CNC' signature, which specifically targets C2 communication patterns.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Application control logs
Why it's wrong here
Application control logs record which applications traversed the firewall, not the command-and-control channel itself, so they cannot corroborate the specific MALWARE-CNC signature. They would be the right source when identifying shadow IT or policy-violating applications rather than validating an intrusion event.
- ✗
URL filtering logs
Why it's wrong here
URL filtering logs show web requests and category verdicts, but command-and-control traffic often bypasses HTTP or uses raw IPs, leaving no URL entry to corroborate the alert. URL filtering is the correct source when investigating web-borne malware downloads or blocked malicious domains.
- ✗
NetFlow records
Why it's wrong here
NetFlow records capture flow metadata such as IPs, ports and byte counts, but no payload or signature detail, so they cannot confirm the command-and-control content the alert flagged. NetFlow is the right source for mapping lateral movement or volumetric anomalies, not validating a specific intrusion signature.
- ✓
DNS query logs
Why this is correct
Command-and-control traffic typically relies on domain resolution, so DNS query logs reveal whether the host contacted the malicious domain named in the alert. Correlating those lookups with the Firepower event confirms or refutes the true positive.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-201 practice question is part of Courseiva's free Cisco 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 200-201 exam.