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200-201 Practice Question: As a SOC analyst, you are reviewing alerts from a…
As a SOC analyst, you are reviewing alerts from a network-based IDS. One alert is for 'ET TROJAN Zeus Trojan Check-in' triggered by traffic from an internal host to an external IP on port 8080. The IDS packet capture shows the traffic is encrypted. You check the host's antivirus logs and find that the host has not been scanned in 30 days. The host belongs to the HR department and typically accesses only internal resources and a few external HR portals. What should be your first action?
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
✓
Block the external IP address at the firewall.
Blocks the external IP, preventing further communication with the potential C2 server. Option D performs a full AV scan and reviews recent process activity to confirm the infection. Both are appropriate first actions: stopping communication while gathering evidence. Option A is incorrect because encryption does not rule out trojan activity. Option C is too aggressive without confirmation and may disrupt operations.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Ignore the alert because it is encrypted and likely a false positive.
Why it's wrong here
Ignoring the alert is dangerous because encryption does not guarantee a false positive; the trojan could be using encrypted traffic to evade detection.
- ✓
Block the external IP address at the firewall.
Why this is correct
Blocking the external IP at the firewall is a reasonable first step to immediately halt communication with the suspected C2 server while further investigation is conducted.
- ✗
Immediately isolate the host from the network by disabling its switch port.
Why it's wrong here
Isolating the host by disabling its switch port is too drastic without confirmation; it may disrupt HR operations and should be done only after verifying compromise.
- ✓
Perform a full antivirus scan on the host and review recent process activity.
Why this is correct
Performing a full antivirus scan and reviewing recent process activity is essential to confirm the trojan infection and understand the scope of compromise.
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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.