This CS0-003 practice question tests your understanding of security operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
During a containment phase of an incident response, the team needs to prevent an infected host from communicating with a command-and-control server. The host is a critical database server that cannot be taken offline. Which of the following containment strategies is most appropriate?
Pull the network cable
Why wrong: Pulling the cable disconnects all network communication.
Disable the database service
Why wrong: Disabling the service would stop database operations.
Isolate the host by VLAN
Why wrong: Isolating the host blocks all traffic, disrupting the database service.
Block the C2 IP at the firewall
Blocking only the C2 IP allows legitimate traffic while preventing command-and-control communication.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Block the C2 IP at the firewall
Blocking the C2 IP at the firewall is the most appropriate strategy because it disrupts the command-and-control communication without taking the critical database server offline. This network-layer containment allows the host to continue serving its database functions while preventing outbound traffic to the malicious IP, aligning with the need for a surgical containment approach.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Pull the network cable
Why it's wrong here
Pulling the cable disconnects all network communication.
Disable the database service
Why it's wrong here
Disabling the service would stop database operations.
Isolate the host by VLAN
Why it's wrong here
Isolating the host blocks all traffic, disrupting the database service.
Block the C2 IP at the firewall
Why this is correct
Blocking only the C2 IP allows legitimate traffic while preventing command-and-control communication.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
CompTIA often tests the distinction between network-level containment (firewall block) and host-level isolation (VLAN or cable pull), trapping candidates who think VLAN isolation is always non-disruptive when it often requires port reconfiguration that can drop active sessions.
Detailed technical explanation
Firewall ACLs operate at Layers 3 and 4, allowing granular control over traffic based on source/destination IP and port. By adding a deny rule for the C2 IP, the firewall drops packets at the network edge without affecting the host's local services or requiring any changes to the host itself. In real-world scenarios, this approach is often combined with logging the blocked traffic for further analysis, and it can be implemented quickly via centralized firewall management systems.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A SOC analyst notices unusual lateral movement in the network at 2 AM. The IR playbook dictates: identify and contain (isolate the affected machine), then eradicate (remove the malware), then recover (restore from backup), then document. Skipping containment before eradication risks the attacker regaining access. Questions like this test the sequence and rationale of incident response phases.
What to study next
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FAQ
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
The correct answer is: Block the C2 IP at the firewall — Blocking the C2 IP at the firewall is the most appropriate strategy because it disrupts the command-and-control communication without taking the critical database server offline. This network-layer containment allows the host to continue serving its database functions while preventing outbound traffic to the malicious IP, aligning with the need for a surgical containment approach.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CS0-003 practice question is part of Courseiva's free CompTIA 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 CS0-003 exam.
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