ISC2 CC Practice Question: Business Continuity, Disaster Recovery, and Incident Response
A financial institution's incident response team is handling a denial-of-service (DoS) attack that is affecting customer access. The team has identified the attack source IPs and implemented filtering rules on the perimeter firewall. Which phase of incident response is being performed?
⚠ Common exam trap
CC often tests the boundaries between containment and eradication, and candidates pick eradication because blocking IPs feels like 'fixing' the problem, when in fact it is a temporary containment measure that does not remove the root cause.
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
✓
Containment
Containment involves limiting the scope and impact of an incident — in this case, implementing firewall filtering rules to block attack source IPs and prevent further damage while the team investigates. This phase focuses on stopping the spread and isolating affected systems, which matches the described action. Eradication would involve removing the root cause (e.g., patching vulnerabilities), and recovery would restore normal 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.
- ✗
Detection
Why it's wrong here
Detection covers identifying that an incident is occurring and scoping it; filtering rules are a containment action, not detection. It is tempting because identifying source IPs feels investigative, but once the team acts on the perimeter firewall to stop the attack spreading, the phase is containment.
- ✗
Recovery
Why it's wrong here
Recovery restores normal operations after containment and eradication, such as bringing services back online and validating them. It is tempting because customer access is the concern, but filtering rules are still an active containment measure; recovery begins once the attack is stopped and systems are rebuilt.
- ✗
Eradication
Why it's wrong here
Eradication removes the root cause, such as malware or a compromised account, from affected systems. It is tempting because blocking malicious traffic sounds like eliminating the threat, but firewall filtering only contains the DoS while it persists; eradication would follow once the attack vector is neutralised.
- ✓
Containment
Why this is correct
Filtering malicious source IPs at the perimeter firewall blocks the attack's traffic, limiting its scope and impact while remediation continues. This matches containment, which stops the spread rather than eradicating the root cause or restoring normal operations.
Go deeper
Related to this question
Learn chapter
Security Operations Basics
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
Impact
Impact is the measure of the potential damage or harm that a risk event could cause to an organization's assets, operations, or reputation.
About these practice questions
One of 989 original CC practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
This CC practice question is part of Courseiva's free ISC2 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 CC exam.