Quick Answer
The answer is VLAN segmentation with ACLs. This is the correct choice because VLANs create separate Layer 2 broadcast domains, isolating traffic between network segments like accounting, HR, and engineering, while ACLs applied to the Layer 3 interface (SVI) enforce granular rules to permit only necessary inter-VLAN communication, such as allowing HR to access a shared server while blocking all other cross-segment traffic. On the ISC2 Certified in Cybersecurity CC exam, this question tests your understanding of network segmentation as a core security control, often appearing in scenarios where you must distinguish between simple VLAN isolation and the need for inter-segment traffic control. A common trap is choosing only VLANs without ACLs, forgetting that VLANs alone block all inter-segment traffic, but ACLs are required to selectively allow necessary communication. Memory tip: think of VLANs as walls between rooms, and ACLs as the locked doors with specific keys—both are needed to control who enters where.
This CC practice question tests your understanding of network security. 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.
An organization has multiple network segments for accounting, HR, and engineering. They want to prevent unauthorized traffic between segments while allowing necessary communication. Which security control should be implemented?
VLAN segmentation with ACLs
VLANs logically segment networks, and ACLs enforce traffic rules between them, achieving the desired control.
Intrusion Detection System (IDS)
Why wrong: An IDS monitors for attacks but does not control traffic between segments.
Proxy server
Why wrong: A proxy server mediates traffic but does not segment internal networks.
Honeypot
Why wrong: A honeypot is a decoy system, not a traffic control mechanism.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
VLAN segmentation with ACLs
VLAN segmentation with ACLs is the correct choice because VLANs create separate broadcast domains at Layer 2, isolating traffic between network segments (accounting, HR, engineering). ACLs applied to the Layer 3 interface (SVI) or trunk ports then enforce granular rules to permit only necessary inter-VLAN communication, such as allowing HR to access a shared server while blocking all other cross-segment traffic.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
VLAN segmentation with ACLs
Why this is correct
VLANs logically segment networks, and ACLs enforce traffic rules between them, achieving the desired control.
Related concept
Read the scenario before looking for a memorised answer.
Intrusion Detection System (IDS)
Why it's wrong here
An IDS monitors for attacks but does not control traffic between segments.
Proxy server
Why it's wrong here
A proxy server mediates traffic but does not segment internal networks.
Honeypot
Why it's wrong here
A honeypot is a decoy system, not a traffic control mechanism.
Common exam traps
ISC2 often tests the distinction between passive detection (IDS) and active prevention (firewall/ACL), so candidates mistakenly choose IDS thinking it blocks traffic, but it only alerts.
Detailed technical explanation
Under the hood, VLANs use 802.1Q trunking to tag frames, and inter-VLAN routing typically occurs through a router-on-a-stick or a Layer 3 switch with SVIs. ACLs applied to these SVIs (e.g., 'access-list 100 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255') filter traffic based on source/destination IP, protocol, and port, providing stateful or stateless control. In a real-world scenario, a misconfigured ACL might accidentally permit all traffic if the implicit deny is omitted, or a VLAN hopping attack could bypass segmentation if trunk ports are not properly secured.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
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FAQ
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
The correct answer is: VLAN segmentation with ACLs — VLAN segmentation with ACLs is the correct choice because VLANs create separate broadcast domains at Layer 2, isolating traffic between network segments (accounting, HR, engineering). ACLs applied to the Layer 3 interface (SVI) or trunk ports then enforce granular rules to permit only necessary inter-VLAN communication, such as allowing HR to access a shared server while blocking all other cross-segment traffic.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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.
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