- A
802.1X authentication
802.1X requires device authentication before access.
- B
Firewall rules
Why wrong: Firewalls control traffic after access is granted.
- C
Port security
Port security restricts MAC addresses on a port.
- D
NAT
Why wrong: NAT translates IP addresses, not for access control.
- E
VLAN segmentation
Why wrong: VLANs do not authenticate devices.
Question 443 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.
An organization wants to ensure that only authorized devices can connect to the wired network. Which TWO methods can be used to enforce this?
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
✓
802.1X authentication
Port security limits the number of MAC addresses on a switch port, and 802.1X requires authentication before granting network access. VLANs segment but do not authenticate, and firewalls filter traffic but not at the access level.
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.
- ✓
802.1X authentication
- ✗
Firewall rules
Why it's wrong here
Firewalls control traffic after access is granted.
- ✓
Port security
Why this is correct
Port security restricts MAC addresses on a port.
Related concept
Access ports place end devices into a single VLAN.
- ✗
NAT
Why it's wrong here
NAT translates IP addresses, not for access control.
- ✗
VLAN segmentation
Why it's wrong here
VLANs do not authenticate devices.
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 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. 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. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Visual reference
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
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: 802.1X authentication — Port security limits the number of MAC addresses on a switch port, and 802.1X requires authentication before granting network access. VLANs segment but do not authenticate, and firewalls filter traffic but not at the access level.
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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