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CS0-003 Practice Question: During a containment phase of an incident…
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?
⚠ Common exam trap
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.
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 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.
Answer analysis
Option-by-option breakdown
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 network cable from a compromised host immediately severs all network connectivity, effectively stopping both malicious command-and-control (C2) traffic and all legitimate business operations. While this achieves containment, it is an overly aggressive method for a database server, causing a complete outage of critical services and potentially hindering forensic data collection from a live system. This drastic action is typically reserved for situations where immediate, complete isolation is paramount and service disruption is acceptable.
- ✗
Disable the database service
Why it's wrong here
Disabling the database service would indeed halt all database operations, preventing further data manipulation or exfiltration through that specific application. However, this action does not address potential compromise at the operating system level or other services running on the host, nor does it directly block the command-and-control (C2) communication channel itself. Furthermore, it unnecessarily disrupts legitimate business functions that rely on the database.
- ✗
Isolate the host by VLAN
Why it's wrong here
Isolating the host by moving it to a quarantined VLAN effectively blocks all network traffic to and from the server, including both malicious command-and-control (C2) communications and legitimate database client connections. While this achieves network containment, it results in a complete outage of the database service for all users. This broad isolation strategy is generally employed when the extent of compromise is unknown or widespread, and immediate, comprehensive network disconnection is required, rather than targeted C2 blocking.
- ✓
Block the C2 IP at the firewall
Why this is correct
Blocking the command-and-control (C2) IP address at the firewall is a precise and effective containment strategy that minimizes impact on legitimate operations. This action specifically prevents the compromised host from communicating with the attacker's infrastructure, thereby stopping further commands or data exfiltration, while allowing all other legitimate database traffic to continue uninterrupted. This targeted approach ensures business continuity while actively mitigating the threat.
Go deeper
Related to this question
Learn chapter
Network Traffic Analysis
Key term
Incident response
Incident response is the structured approach an organization uses to identify, contain, and recover from cybersecurity incidents like data breaches or ransomware attacks.
Key term
Firewall
A firewall is a network security system that monitors and controls incoming and outgoing traffic based on predetermined security rules to protect trusted internal networks from untrusted external networks.
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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.