easyMultiple ChoiceObjective-mapped
CS0-003 Practice Question: A security team is reviewing firewall logs and…
A security team is reviewing firewall logs and identifies traffic to a known malicious IP address from an internal workstation running a critical business application that cannot be interrupted. Which of the following is the most appropriate immediate action?
⚠ Common exam trap
CompTIA often tests the principle of 'least disruption' in incident response, where candidates mistakenly choose to shut down or disconnect the system (options B or C) because they focus solely on containment, forgetting the critical business application's availability requirement.
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
✓
Add a firewall rule to block the malicious IP
Adding a firewall rule to block the malicious IP is the most appropriate immediate action because it stops the outbound traffic to the known malicious address without disrupting the critical business application running on the workstation. This approach maintains availability (a key CIA triad principle) while mitigating the threat at the network layer, which is faster and less invasive than host-level changes. It also preserves the workstation's state for potential forensic analysis.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Add a firewall rule to block the malicious IP
Why this is correct
Implementing a new firewall rule to explicitly deny all traffic from the identified malicious IP address is a precise and effective containment strategy. This action operates at the network layer, preventing further unauthorized communication without disrupting legitimate business applications or services running on the affected workstation. It directly addresses the source of the observed malicious activity, isolating the threat while maintaining operational continuity.
- ✗
Shut down the workstation
Why it's wrong here
Shutting down the workstation is an overly aggressive response that would immediately interrupt any critical business applications or services running on it. While it would stop all activity, including malicious communication, it causes significant operational disruption, which is often unacceptable when more targeted containment methods are available. This action should be reserved for situations where the threat cannot be contained otherwise or poses an immediate, severe risk to the system's integrity that outweighs business continuity.
- ✗
Disconnect the network cable
Why it's wrong here
Disconnecting the network cable physically isolates the workstation from the entire network, effectively stopping all communication, both malicious and legitimate. This action, while immediately containing the network-based threat, simultaneously renders any critical business application running on the workstation unusable due to its reliance on network connectivity. It represents a complete loss of service, which is generally avoided in favor of more surgical containment methods that preserve operational functionality.
- ✗
Run an antivirus scan
Why it's wrong here
Running an antivirus scan is primarily a detection and remediation activity aimed at identifying and removing malware from a system, not an immediate containment strategy for ongoing network communication. While important for post-incident cleanup, an antivirus scan may not stop an active, established malicious network connection or prevent further communication in real-time. It does not directly block network traffic at the perimeter or host level, making it ineffective for immediate containment of observed malicious IP activity.
Go deeper
Related to this question
Learn chapter
Threat Intelligence and Threat Hunting
Key term
Firewall rule
A firewall rule is a set of conditions that tells a firewall which network traffic to allow or block based on attributes like source, destination, port, and protocol.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CS0-004 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 CS0-004 exam.