Question 185 of 503
Incident Response and ManagementmediumMultiple ChoiceObjective-mapped

CS0-003 Incident Response and Management Practice Question

This CS0-003 practice question tests your understanding of incident response and management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.

You are a security analyst for a mid-sized financial services company. At 2:30 PM, the endpoint detection and response (EDR) console alerts on three workstations in the accounting department, indicating that files are being encrypted with a '.encrypt' extension and a ransom note named 'READ_ME_NOW.html' has been dropped. The workstations are connected to a file server that hosts shared financial records and a domain controller that handles authentication. The file server and domain controller have not shown signs of compromise yet. Your incident response plan states that containment must begin within 15 minutes of detection. Based on your analysis of the EDR telemetry, the encryption process appears to be spreading via SMB connections from the first infected workstation. Which of the following is the BEST immediate containment action to prevent further spread while preserving evidence?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "best"

    Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

  • Clue: "first"

    Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

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

Immediately isolate the three workstations by disconnecting their network cables at the patch panel or disabling their switch ports.

Option A is correct because immediately isolating the three infected workstations at the network level (disconnecting cables or disabling switch ports) stops the SMB-based encryption propagation without destroying volatile forensic data. This containment action preserves the running processes, memory, and disk state for later analysis, which would be lost if the systems were powered off. The 15-minute containment window makes network isolation the fastest and most effective method to halt lateral movement while maintaining evidence integrity.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Immediately isolate the three workstations by disconnecting their network cables at the patch panel or disabling their switch ports.

    Why this is correct

    Isolating at the network level stops lateral movement and preserves the system state for evidence collection.

    Clue confirmation

    The clue words "best", "first" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Shut down the file server and domain controller to protect critical systems from potential encryption.

    Why it's wrong here

    Shutting down these servers could disrupt operations and destroy volatile evidence; also, they are not yet compromised, so isolating them may be premature without evidence preservation of the infected workstations.

  • Power off the three infected workstations immediately to contain the encryption process.

    Why it's wrong here

    Powering off the workstations destroys volatile memory evidence that could be critical for understanding the attack vector and scope.

  • Apply the latest SMB vulnerability patch to the file server and domain controller to block the propagation vector.

    Why it's wrong here

    Patching does not contain the current infection; the encryption may continue locally on the workstations. It also does not address the immediate threat of lateral movement from already compromised systems.

Common exam traps

Common exam trap: answer the scenario, not the keyword

CompTIA often tests the distinction between containment (stopping the spread) and eradication (removing the threat), and the trap here is that candidates confuse immediate containment with remediation actions like patching or shutting down systems, which either take too long or destroy evidence.

Detailed technical explanation

How to think about this question

SMB (Server Message Block) propagation typically uses named pipes or scheduled tasks over TCP/445 to copy and execute ransomware payloads. Network isolation at the switch port (e.g., using `shutdown` interface command on Cisco switches or disabling the port in the VLAN) instantly terminates all Layer 2 and Layer 3 communication, cutting off the SMB sessions mid-stream. This approach is preferred over OS-level isolation (e.g., Windows Firewall) because it cannot be bypassed by malware with elevated privileges and ensures the endpoint cannot send any further malicious packets.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Related practice questions

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FAQ

Questions learners often ask

What does this CS0-003 question test?

Incident Response and Management — This question tests Incident Response and Management — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Immediately isolate the three workstations by disconnecting their network cables at the patch panel or disabling their switch ports. — Option A is correct because immediately isolating the three infected workstations at the network level (disconnecting cables or disabling switch ports) stops the SMB-based encryption propagation without destroying volatile forensic data. This containment action preserves the running processes, memory, and disk state for later analysis, which would be lost if the systems were powered off. The 15-minute containment window makes network isolation the fastest and most effective method to halt lateral movement while maintaining evidence integrity.

What should I do if I get this CS0-003 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "best", "first". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 30, 2026

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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.