- A
Using encryption protocols (e.g., IPsec, TLS)
Correct. Encryption renders sniffed data confidential.
- B
Implementing VLANs
Why wrong: VLANs segment traffic but do not encrypt it.
- C
Disabling unused ports on the switch
Why wrong: Reduces physical access but does not protect against sniffing on active ports.
- D
Deploying an intrusion detection system
Why wrong: IDS can detect sniffing but does not prevent it.
Question 994 of 1,000
ISC2 CC Network Security Practice Question
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.
Which security control would best mitigate the risk of network sniffing on a wired LAN 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
✓
Using encryption protocols (e.g., IPsec, TLS)
Encrypting traffic (e.g., using HTTPS, VPN) makes sniffed data unreadable.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Using encryption protocols (e.g., IPsec, TLS)
Why this is correct
Correct. Encryption renders sniffed data confidential.
Related concept
Access ports place end devices into a single VLAN.
- ✗
Implementing VLANs
Why it's wrong here
VLANs segment traffic but do not encrypt it.
- ✗
Disabling unused ports on the switch
Why it's wrong here
Reduces physical access but does not protect against sniffing on active ports.
- ✗
Deploying an intrusion detection system
Why it's wrong here
IDS can detect sniffing but does not prevent it.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
- Access ports place end devices into a single VLAN.
- Trunk ports carry multiple VLANs between switches.
- Allowed VLAN lists decide which VLANs can cross a trunk.
- Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
- Use show vlan brief to verify access VLANs.
- Use show interfaces trunk to verify trunk state and allowed VLANs.
- Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related CC questions on switching, trunking, and access-port configuration.
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FAQ
Questions learners often ask
What does this CC question test?
Network Security — This question tests Network Security — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: Using encryption protocols (e.g., IPsec, TLS) — Encrypting traffic (e.g., using HTTPS, VPN) makes sniffed data unreadable.
What should I do if I get this CC question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related CC questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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Last reviewed: Jul 4, 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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