- A
802.1X
802.1X authenticates devices before allowing them to send traffic, providing strong access control.
- B
Port security
Why wrong: Port security restricts the number of allowed MAC addresses but does not authenticate the device; it can be bypassed with MAC spoofing.
- C
MAC filtering
Why wrong: MAC filtering simply allows or denies traffic based on MAC addresses and is not a strong authentication mechanism.
- D
Storm control
Why wrong: Storm control limits broadcast, multicast, or unknown unicast traffic to prevent denial of service, not unauthorized access.
Question 469 of 520
How Does 802.1X Authenticate Devices on Switch Ports?
This N10-009 practice question tests your understanding of network security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 network administrator wants to prevent unauthorized devices from connecting to the network through a switch port. Which security feature should be enabled on the switch?
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 the correct answer because it provides port-based network access control (PNAC) that authenticates devices before granting network access. It uses the Extensible Authentication Protocol (EAP) over LAN (EAPoL) to communicate with a RADIUS server, ensuring only authorized users or devices can connect through the switch port. This prevents unauthorized devices from accessing the network at Layer 2, regardless of MAC address or IP configuration.
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.
- ✓
802.1X
Why this is correct
802.1X authenticates devices before allowing them to send traffic, providing strong access control.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Port security
Why it's wrong here
Port security restricts the number of allowed MAC addresses but does not authenticate the device; it can be bypassed with MAC spoofing.
When this WOULD be correct
A question asking 'Which feature prevents MAC flooding attacks by limiting the number of MAC addresses on a port?' would make port security the correct answer.
- ✗
MAC filtering
Why it's wrong here
MAC filtering simply allows or denies traffic based on MAC addresses and is not a strong authentication mechanism.
When this WOULD be correct
A network administrator wants to restrict network access to only devices with known MAC addresses on a small, static network without user authentication requirements.
- ✗
Storm control
Why it's wrong here
Storm control limits broadcast, multicast, or unknown unicast traffic to prevent denial of service, not unauthorized access.
When this WOULD be correct
A network administrator wants to prevent a broadcast storm from overwhelming the network. Which feature should be enabled on the switch?
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 authenticates devices before allowing them to send traffic, providing strong access control.
✗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 devices; it can be bypassed by spoofing a learned MAC address.
★ When this WOULD be the correct answer
A question asking 'Which feature prevents MAC flooding attacks by limiting the number of MAC addresses on a port?' would make port security the correct answer.
Why candidates choose this
Candidates often confuse port security with device authentication because both control access based on MAC addresses, but port security lacks the authentication mechanism that 802.1X provides.
✗MAC filteringWrong answer — click to see why▾
Why this is wrong here
MAC filtering controls access based on MAC addresses but does not authenticate users or devices dynamically; it can be bypassed by MAC spoofing and does not integrate with authentication servers like RADIUS.
★ When this WOULD be the correct answer
A network administrator wants to restrict network access to only devices with known MAC addresses on a small, static network without user authentication requirements.
Why candidates choose this
Candidates confuse MAC filtering with port-based authentication, assuming that filtering MAC addresses is sufficient to prevent unauthorized devices, but it lacks the dynamic authentication and encryption of 802.1X.
✗Storm controlWrong answer — click to see why▾
Why this is wrong here
Storm control is used to limit broadcast, multicast, or unknown unicast traffic to prevent network storms, not to prevent unauthorized devices from connecting to a switch port.
★ When this WOULD be the correct answer
A network administrator wants to prevent a broadcast storm from overwhelming the network. Which feature should be enabled on the switch?
Why candidates choose this
Candidates may confuse 'storm control' with controlling access or security, thinking it prevents unauthorized traffic, but it actually manages traffic volume, not device authentication.
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 or MAC filtering with true authentication, but the key point is that 802.1X is the only feature that performs per-device authentication against a central server, not just static MAC-based controls.
Detailed technical explanation
How to think about this question
802.1X operates in three roles: supplicant (client), authenticator (switch), and authentication server (RADIUS). The switch initially places the port in an unauthorized state, allowing only EAPoL frames; after successful authentication, the port transitions to an authorized state and dynamically opens for user traffic. In real-world deployments, 802.1X is often combined with MAB (MAC Authentication Bypass) for legacy devices that do not support an 802.1X supplicant.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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 the correct answer because it provides port-based network access control (PNAC) that authenticates devices before granting network access. It uses the Extensible Authentication Protocol (EAP) over LAN (EAPoL) to communicate with a RADIUS server, ensuring only authorized users or devices can connect through the switch port. This prevents unauthorized devices from accessing the network at Layer 2, regardless of MAC address or IP configuration.
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 →
Same concept, more angles
2 more ways this is tested on N10-009
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network administrator needs to ensure that only authorized devices can connect to the wired network. Each user must authenticate using their domain credentials. Which of the following should be implemented?
hard- A.MAC filtering
- ✓ B.802.1X with EAP-TLS
- C.WPA2-PSK
- D.Port security
Why B: 802.1X with EAP-TLS is correct because it provides port-based network access control that requires each user to authenticate using their domain credentials (via a RADIUS server) before the switch port is opened for traffic. EAP-TLS uses mutual authentication with digital certificates, ensuring only authorized devices and users gain access to the wired network.
Variation 2. A network administrator wants to prevent unauthorized devices from connecting to the company's Ethernet ports. The company uses a centralized authentication server. Which IEEE standard should be implemented?
medium- ✓ A.802.1X
- B.802.11i
- C.802.3af
- D.802.1Q
Why A: 802.1X is the IEEE standard for port-based Network Access Control (NAC) that authenticates devices before granting access to an Ethernet port. It uses a centralized authentication server (typically RADIUS) to verify credentials, preventing unauthorized devices from connecting to the network. This directly matches the requirement of controlling access at the port level with a centralized server.
Keep practising
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Last reviewed: Jun 11, 2026
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