ISC2 CC Network Security Practice Question
A network administrator needs to segment traffic and isolate sensitive systems. Which two technologies can achieve this? (Choose TWO.)
⚠ Common exam trap
The CC exam often tests the difference between segmentation technologies (VLANs, subnetting) and security controls (IDS, firewalls) or design patterns (DMZ), tricking candidates into selecting tools that monitor or filter rather than segment.
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
✓
VLANs
VLANs (B) are correct because they logically segment a switched network at Layer 2, allowing the administrator to isolate sensitive systems into separate broadcast domains and control traffic between them via inter-VLAN routing or ACLs. Subnetting (E) is correct because dividing a network into smaller IP subnets at Layer 3 separates traffic into distinct address ranges, enabling isolation and controlled routing between sensitive systems and the rest of the network. An IDS (A) only monitors and alerts on malicious activity; it does not segment or isolate traffic. A stateful firewall (C) filters traffic based on connection state but is a control mechanism rather than a segmentation technology itself. A DMZ (D) is a perimeter network design that exposes public-facing services, not a general-purpose segmentation method for isolating internal sensitive systems.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Intrusion Detection System
Why it's wrong here
An IDS only monitors and alerts on suspicious traffic; it neither segments networks nor isolates hosts, so sensitive systems remain reachable. It is tempting because it is a security control that inspects traffic, and would be correct where the requirement is detecting intrusions rather than dividing the network.
- ✓
VLANs
Why this is correct
VLANs logically partition a single physical network into isolated broadcast domains at Layer 2, so sensitive systems exchange traffic only with permitted members. This directly satisfies the stem's segmentation and isolation requirement, restricting lateral movement without additional hardware.
- ✗
Stateful firewall
Why it's wrong here
A stateful firewall filters traffic by connection state but does not itself create isolated network segments; segmentation requires separate subnets or VLANs with enforced boundaries. It is tempting because firewalls control traffic between zones, and would be correct where policy enforcement between existing segments is the requirement.
- ✗
DMZ
Why it's wrong here
A DMZ is a single perimeter subnet hosting public-facing services; it does not segment internal traffic or isolate sensitive internal systems from each other. It is tempting because it separates exposed servers from the internal network, and would be correct where the requirement is shielding internal hosts from internet-facing services.
- ✓
Subnetting
Why this is correct
Subnetting divides one physical network into separate logical IP subnets, letting the administrator isolate sensitive systems and control traffic between segments via routing and ACLs. This directly satisfies the requirement to segment traffic and isolate sensitive systems.
Visual reference
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Related to this question
Learn chapter
Network Security Foundations
Key term
VLAN
A VLAN (Virtual Local Area Network) is a logical grouping of network devices that behave as if they are on the same physical network segment, regardless of their actual physical location.
Key term
IDS
An IDS is a security system that monitors network or system traffic for suspicious activity and alerts administrators to potential threats, but does not actively block them.
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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
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.