easyMultiple Choice
Incident Response: First Action Is to Block Source IP
A security analyst receives an alert that an employee's workstation is generating outbound traffic to a known malware command-and-control IP address at 3:00 AM. According to the company's incident response policy, what is the FIRST action the analyst should take?
⚠ Common exam trap
Cisco often tests the containment-first principle in incident response, and the trap here is that candidates rush to eradicate the malware (reimage) or fix the vulnerability (patch) instead of stopping the active threat by isolating the host.
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
✓
Isolate the workstation from the network by disabling the switch port.
The first action is to isolate the workstation from the network by disabling the switch port. This immediately stops the outbound command-and-control (C2) traffic, preventing data exfiltration and further compromise, while preserving the system state for forensic analysis. According to the incident response policy, containment takes precedence over eradication or recovery to limit damage.
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 workstation from the network by disabling the switch port.
Why this is correct
Disabling the switch port immediately severs the workstation's command-and-control channel, satisfying the policy's containment-first requirement before forensic capture or eradication. Network isolation at layer 2 stops further exfiltration and payload retrieval while preserving volatile memory and disk state for later investigation, unlike shutdown or remediation actions that would destroy evidence.
- ✗
Reimage the workstation immediately to remove the malware.
Why it's wrong here
Reimaging destroys volatile evidence such as memory-resident malware and network connections before containment and forensic capture, contradicting the policy's first step. It is tempting because reimaging is the eventual remediation for a compromised host, once evidence has been preserved and the incident scoped.
- ✗
Apply the latest security patches to the workstation.
Why it's wrong here
Patching is not an immediate containment step.
- ✗
Call the employee to ask if they are working late.
Why it's wrong here
Phoning the employee does not isolate the compromised host or stop the outbound command-and-control traffic, and it risks tipping off an insider. It is tempting because confirming whether legitimate late work explains the 3:00 AM activity seems a low-impact first check.
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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.