ISC2 CC Network Security Practice Question
A company's web server is experiencing a high volume of traffic from thousands of different IP addresses, causing service degradation. The security team determines it is a distributed denial-of-service (DDoS) attack. Which mitigation strategy is most effective for this scenario?
⚠ Common exam trap
The trap here is assuming that any security device (like an IPS or host firewall) can stop a DDoS; volumetric attacks require specialized, high-capacity mitigation that only cloud or ISP-based scrubbing services typically provide.
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
✓
Use a cloud-based DDoS mitigation service.
A cloud-based DDoS mitigation service is specifically designed to absorb and filter large volumetric attacks by leveraging distributed scrubbing centers and high bandwidth. It can handle thousands of source IPs and protect the origin server without requiring on-premises hardware upgrades. This is the most effective and scalable solution for the described scenario.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure an intrusion prevention system (IPS) to block the attack.
Why it's wrong here
An IPS can detect and block some application-layer attacks, but it is not designed to handle high-volume volumetric DDoS attacks. The IPS itself could become a bottleneck or be overwhelmed by the traffic volume. It lacks the bandwidth and distributed architecture needed to mitigate large-scale DDoS.
- ✓
Use a cloud-based DDoS mitigation service.
Why this is correct
Cloud-based DDoS mitigation services divert traffic to scrubbing centers that filter malicious packets and forward only clean traffic to the origin server. They have massive bandwidth and can absorb volumetric attacks, making them ideal for distributed attacks. This preserves server availability and scales beyond on-premises capabilities.
- ✗
Increase the web server's bandwidth and CPU resources.
Why it's wrong here
Scaling up the server might temporarily handle more traffic, but a sufficiently large DDoS can exhaust any fixed resources. This approach is costly and does not address the root cause; the attack traffic still reaches the server. It is not a sustainable or effective mitigation for DDoS.
- ✗
Install a host-based firewall on the web server.
Why it's wrong here
A host-based firewall can block specific IP addresses, but with thousands of distributed sources, it would quickly become overwhelmed and the server's resources would still be consumed processing the attack traffic. It cannot scale to filter a large DDoS. A network or cloud-based scrubbing solution is required.
Visual reference
Go deeper
Related to this question
Key term
Distributed Denial-of-service
A cyberattack where many compromised computers flood a target system with traffic, making it unavailable to legitimate users.
Key term
Denial-of-service
A Denial-of-service (DoS) attack is an attempt to make a computer, network, or online service unavailable to its intended users by overwhelming it with fake traffic or requests.
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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
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