The answer is the 'authentication failed action authorize vlan 999' command. This configuration is correct because it instructs the switch port to place endpoints that fail both 802.1X and MAB into a restricted VLAN, directly fulfilling the security policy requirement for unauthenticated devices. On the Cisco DCCOR and CCNP Data Center Core 350-601 exam, this question tests your understanding of the 802.1X/MAB failure fallback sequence and the specific command syntax for a restricted VLAN with authentication failed action. A common trap is confusing this with the 'authentication event fail action' command, which handles pre-authentication failures rather than post-authentication failures. Remember the memory tip: "Failed auth? Authorize a VLAN" — the keyword 'authorize' is what places the endpoint into the restricted VLAN after both authentication methods have been exhausted.
350-601 Security Practice Question
This 350-601 practice question tests your understanding of security. 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.
An organization is deploying Cisco ISE for 802.1X authentication on Cisco Nexus switches. Some endpoints fail authentication and fall back to the MAB. The security policy requires that endpoints failing both 802.1X and MAB be placed in a restricted VLAN. Which configuration is needed on the switch port?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
authentication failed action authorize vlan 999
Option C is correct because the 'authentication failed action authorize vlan 999' command configures the switch port to place endpoints that fail both 802.1X and MAB into a restricted VLAN (VLAN 999). This directly meets the security policy requirement for endpoints that cannot authenticate via either method.
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.
✗
authentication order dot1x mab
Why it's wrong here
This sets the order of methods, not the failure action.
✗
dot1x timeout tx-period 30
Why it's wrong here
This sets the retransmission timer, not the failure action.
✓
authentication failed action authorize vlan 999
Why this is correct
This command places the port into the specified VLAN (restricted) after authentication failure.
Related concept
Read the scenario before looking for a memorised answer.
✗
authentication event server dead action authorize vlan 999
Why it's wrong here
This action is for when the server is unreachable, not for authentication failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing 'authentication failed action' (which handles authentication failure) with 'authentication event server dead action' (which handles server unavailability), leading candidates to pick Option D when the scenario explicitly describes endpoints failing authentication, not a server outage.
Detailed technical explanation
How to think about this question
The 'authentication failed action authorize vlan' command is part of Cisco's Identity-Based Networking Services (IBNS) 2.0, which uses a stateful authentication manager to handle multi-method authentication. When both 802.1X and MAB fail, the switch places the port into the specified restricted VLAN, often used for guest or quarantine access, and the port remains in that VLAN until re-authentication or administrative action. This command is distinct from 'authentication event' commands, which react to server or link events rather than authentication outcomes.
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 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: authentication failed action authorize vlan 999 — Option C is correct because the 'authentication failed action authorize vlan 999' command configures the switch port to place endpoints that fail both 802.1X and MAB into a restricted VLAN (VLAN 999). This directly meets the security policy requirement for endpoints that cannot authenticate via either method.
What should I do if I get this 350-601 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 →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 350-601 practice question is part of Courseiva's free Cisco 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 350-601 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.