Question 1,005 of 2,015

802.1X and TrustSec →mediumDrag & DropObjective-mapped

Quick Answer

The answer is that the switch applies a downloadable ACL to the port as the final step in the MAB fallback flow. This is correct because MAC Authentication Bypass serves as a fallback mechanism when 802.1X authentication fails; the switch first detects the MAC address, then sends a RADIUS Access-Request to ISE, which checks its MAC database and returns an Access-Accept containing a downloadable ACL, and only after receiving this does the switch apply the ACL to enforce policy. On the ENCOR 350-401 exam, this drag-and-drop task tests your understanding of the sequential logic in AAA fallback scenarios, where a common trap is confusing the RADIUS reply with the switch’s local application of the ACL. Remember that the switch does not create the ACL—it merely applies what ISE sends. A helpful memory tip is “Detect, Request, Accept, Apply” to recall the order: the switch detects the MAC, requests authentication, receives an accept with the ACL, and finally applies it to the port.

350-401 802.1X and TrustSec Practice Question

This 350-401 practice question tests your understanding of 802.1x and trustsec. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.

Drag and drop the steps of MAB (MAC Authentication Bypass) fallback flow into the correct order, from first to last.

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

Question 1mediumdrag order

Full question →

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

✓

Switch detects link up and no EAP response

MAB is used as a fallback when 802.1X fails; the switch detects the MAC, sends a RADIUS Access-Request, ISE checks the MAC database, returns an Access-Accept with a downloadable ACL, and the switch applies the ACL.

Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.

Common exam traps

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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.

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 350-401 questions on access control and AAA configuration.

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FAQ

Questions learners often ask

What does this 350-401 question test?

802.1X and TrustSec — This question tests 802.1X and TrustSec — Authentication checks who the user is..

What is the correct answer to this question?

The correct answer is: Switch detects link up and no EAP response — MAB is used as a fallback when 802.1X fails; the switch detects the MAC, sends a RADIUS Access-Request, ISE checks the MAC database, returns an Access-Accept with a downloadable ACL, and the switch applies the ACL.

What should I do if I get this 350-401 question wrong?

Are there clue words in this question I should notice?

Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

What is the key concept behind this question?

Authentication checks who the user is.

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Same concept, more angles

1 more ways this is tested on 350-401

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. Drag and drop the steps of MAB (MAC Authentication Bypass) fallback flow into the correct order, from first to last.

medium

✓ A.Host connects; switch detects link up
✓ B.802.1X times out; switch starts MAB
✓ C.Switch sends RADIUS Access-Request with MAC as credentials
✓ D.ISE validates MAC in endpoint database
✓ E.ISE returns Access-Accept; switch places port in authorized VLAN

Why A: MAB is a fallback method when 802.1X fails: the switch detects the host MAC, sends a RADIUS Access-Request with the MAC as username/password, ISE checks the MAC against its database, and then either grants access (placing the port in the authorized VLAN) or denies it.

Last reviewed: Jun 18, 2026

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