The answer is that the switch port is configured as a trunk port, which is the most likely cause of the 802.1X failure on trunk port. By default, Cisco switches do not support 802.1X authentication on trunk ports because EAPOL frames are not forwarded across trunk links; the switch expects native VLAN traffic and does not process EAPOL-Start messages from the supplicant, so the client never receives an EAP-Request/Identity response. On the Cisco SCOR / CCNP Security Core 350-701 exam, this scenario tests your understanding that 802.1X is designed for access ports, and a common trap is overlooking the port mode when troubleshooting authentication failures. Remember the memory tip: "Trunks don't talk EAPOL" — if you see EAPOL-Start with no reply, always verify the port is an access port, not a trunk.
350-701 Practice Question: Secure Network Access, Visibility and Enforcement
This 350-701 practice question tests your understanding of secure network access, visibility and enforcement. 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 engineer notices that some Windows 10 clients fail to authenticate via 802.1X after a recent OS update. The supplicant shows 'EAPOL-Start' but never receives an EAP-Request/Identity. The switch port is configured with 'authentication port-control auto' and 'dot1x pae authenticator'. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The switch port is configured as a trunk port
Option B is correct because if the switch port is configured as a trunk, 802.1X is not supported on trunk ports by default. Option A is wrong because SNMP does not affect EAPOL. Option C is wrong because global authentication mode 'none' would not affect a single port. Option D is wrong because MAB is a fallback method, not the cause of EAPOL-Start not being answered.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The switch port is configured as a trunk port
Why this is correct
802.1X is not supported on trunk ports by default. The switch will not respond to EAPOL-Start on trunk ports.
Clue confirmation
The clue words "most likely", "never" in the question point toward this answer.
Related concept
Authentication checks who the user is.
✗
The switch has 'aaa authentication dot1x default none' globally
Why it's wrong here
This would allow all without authentication, but the switch would still respond to EAPOL.
✗
The switch port is configured with 'authentication order mab dot1x'
Why it's wrong here
MAB is a fallback method and does not prevent the switch from responding to EAPOL.
✗
The switch is configured with 'snmp-server community' which disables 802.1X
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-701 questions on access control and AAA configuration.
Secure Network Access, Visibility and Enforcement — This question tests Secure Network Access, Visibility and Enforcement — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: The switch port is configured as a trunk port — Option B is correct because if the switch port is configured as a trunk, 802.1X is not supported on trunk ports by default. Option A is wrong because SNMP does not affect EAPOL. Option C is wrong because global authentication mode 'none' would not affect a single port. Option D is wrong because MAB is a fallback method, not the cause of EAPOL-Start not being answered.
What should I do if I get this 350-701 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-701 questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "most likely", "never". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Authentication checks who the user is.
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