mediumMultiple Choice
200-201 Practice Question: An IDS detected the following signature match:…
An IDS detected the following signature match: "ET TROJAN Zeus variant outbound connection to C2 server". The destination IP is flagged as a known malicious host. What should the analyst do FIRST?
⚠ Common exam trap
Cisco often tests the principle that validation via packet capture must precede any containment or blocking action, trapping candidates who jump to immediate remediation without confirming the alert's accuracy.
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
✓
Open the packet capture associated with the alert
The first step in incident response after an IDS alert is to validate the alert by examining the associated packet capture (PCAP). This allows the analyst to confirm whether the traffic truly matches the Zeus C2 signature, check for false positives, and gather contextual details such as payload content, timing, and protocol behavior. Without this validation, any subsequent action (blocking, isolating) could be premature or based on incomplete information.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Block the destination IP at the firewall
Why it's wrong here
Blocking the destination IP addresses the C2 channel but leaves the compromised host communicating and does not confirm or scope the infection; the analyst must first investigate the source host. It is tempting as immediate threat neutralisation, and would be correct as a containment step after validating the compromise.
- ✓
Open the packet capture associated with the alert
Why this is correct
The signature only flags a possible match; opening the associated packet capture lets the analyst verify the actual traffic, confirm the C2 connection, and gather evidence before escalating, isolating, or blocking anything based on a single alert.
- ✗
Ignore the alert because signatures can produce false positives
Why it's wrong here
Dismissing the alert ignores that the destination IP is confirmed malicious, so the signature match plus threat intelligence warrants investigation rather than closure. It is tempting because signature-based IDS does generate false positives, and ignoring would be defensible only if the destination were unverified and the traffic benign.
- ✗
Isolate the source host from the network immediately
Why it's wrong here
Isolating the host is a containment action, not the first step; the analyst must first validate the alert and scope the incident, since premature isolation can destroy volatile evidence and disrupt business operations. It is tempting because containment feels urgent, and would be correct once the compromise is confirmed and evidence preserved.
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JA
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.