- A
MAC address filtering
Why wrong: MAC filtering can be bypassed by MAC spoofing and is not a strong authentication method.
- B
Port security
Why wrong: Port security limits the number of MAC addresses per port, but it does not authenticate users and can be circumvented.
- C
802.1X
802.1X requires user or device authentication via an authentication server (RADIUS) before the switch port becomes active.
- D
Dynamic ARP Inspection
Why wrong: DAI prevents ARP spoofing attacks, but it does not control initial network access.
Question 113 of 520
N10-009 Network Security Practice Question
This N10-009 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.
A company wants to prevent unauthorized users from plugging into network jacks and gaining access to the wired network. Which of the following security mechanisms should be implemented at the switch level?
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
802.1X is a port-based Network Access Control (NAC) standard (IEEE 802.1X) that authenticates devices before granting full network access. When a device plugs into a switch port, the switch (as the authenticator) blocks all traffic except EAPoL (Extensible Authentication Protocol over LAN) frames until the device successfully authenticates via a RADIUS server. This prevents unauthorized users from gaining network access simply by connecting to a live jack.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
MAC address filtering
Why it's wrong here
MAC filtering can be bypassed by MAC spoofing and is not a strong authentication method.
When this WOULD be correct
A company wants to allow only specific devices (e.g., known printers or servers) to connect to certain switch ports, and the network is small with static MAC assignments. The question would specify that MAC spoofing is not a concern and that dynamic authentication is not required.
- ✗
Port security
Why it's wrong here
Port security limits the number of MAC addresses per port, but it does not authenticate users and can be circumvented.
When this WOULD be correct
A question asks: 'Which switch feature prevents MAC flooding attacks by limiting the number of MAC addresses learned on a port?' or 'Which security mechanism blocks traffic from unknown MAC addresses on a port?'
- ✓
802.1X
- ✗
Dynamic ARP Inspection
Why it's wrong here
DAI prevents ARP spoofing attacks, but it does not control initial network access.
When this WOULD be correct
A company wants to prevent ARP spoofing attacks on its network where an attacker sends fake ARP messages to intercept traffic. Implementing Dynamic ARP Inspection on switches would validate ARP packets and drop invalid ones, mitigating the attack.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓802.1XCorrect answer▾
Why this is correct
802.1X requires user or device authentication via an authentication server (RADIUS) before the switch port becomes active.
✗MAC address filteringWrong answer — click to see why▾
Why this is wrong here
MAC address filtering only restricts traffic based on MAC addresses, but it does not authenticate users or prevent unauthorized devices from connecting if the MAC address is spoofed or allowed. It also does not enforce per-user authentication at the switch port level.
★ When this WOULD be the correct answer
A company wants to allow only specific devices (e.g., known printers or servers) to connect to certain switch ports, and the network is small with static MAC assignments. The question would specify that MAC spoofing is not a concern and that dynamic authentication is not required.
Why candidates choose this
Candidates often confuse MAC address filtering with port security, thinking that filtering MACs is sufficient to prevent unauthorized access, but they overlook that 802.1X provides stronger, user-based authentication.
✗Port securityWrong answer — click to see why▾
Why this is wrong here
Port security limits the number of MAC addresses per port but does not authenticate users; it can be bypassed by spoofing allowed MAC addresses, so it does not prevent unauthorized users from plugging in.
★ When this WOULD be the correct answer
A question asks: 'Which switch feature prevents MAC flooding attacks by limiting the number of MAC addresses learned on a port?' or 'Which security mechanism blocks traffic from unknown MAC addresses on a port?'
Why candidates choose this
Candidates confuse port security with user authentication, thinking that restricting MAC addresses is sufficient to prevent unauthorized access, but it lacks per-user authentication and can be easily spoofed.
✗Dynamic ARP InspectionWrong answer — click to see why▾
Why this is wrong here
Dynamic ARP Inspection (DAI) is used to prevent ARP spoofing attacks by validating ARP packets against a trusted database, not to control physical access to network jacks. It does not authenticate users or devices attempting to connect to the switch.
★ When this WOULD be the correct answer
A company wants to prevent ARP spoofing attacks on its network where an attacker sends fake ARP messages to intercept traffic. Implementing Dynamic ARP Inspection on switches would validate ARP packets and drop invalid ones, mitigating the attack.
Why candidates choose this
Candidates may confuse DAI with a security mechanism that controls network access because it involves inspecting packets at the switch level, but it specifically addresses ARP-related threats, not physical port access.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse port security (which only limits MAC addresses) with 802.1X (which provides actual authentication), leading them to pick port security because it sounds like it 'secures the port' at the switch level.
Detailed technical explanation
How to think about this question
802.1X uses three roles: supplicant (client), authenticator (switch), and authentication server (RADIUS). The switch places the port in an unauthorized state, allowing only 802.1X EAPoL frames (EtherType 0x888E) to pass. After successful authentication, the switch dynamically opens the port, often applying a specific VLAN or ACL based on RADIUS attributes. A common real-world scenario is a conference room jack where 802.1X ensures only corporate devices with valid certificates or credentials can connect, while guests are redirected to a captive portal or isolated VLAN.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
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.
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FAQ
Questions learners often ask
What does this N10-009 question test?
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 802.1X — 802.1X is a port-based Network Access Control (NAC) standard (IEEE 802.1X) that authenticates devices before granting full network access. When a device plugs into a switch port, the switch (as the authenticator) blocks all traffic except EAPoL (Extensible Authentication Protocol over LAN) frames until the device successfully authenticates via a RADIUS server. This prevents unauthorized users from gaining network access simply by connecting to a live jack.
What should I do if I get this N10-009 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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Last reviewed: Jun 11, 2026
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