The answer is that AAA must be enabled on the switch, a RADIUS server must be configured, and 802.1X must be globally enabled on the switch. These three prerequisites are essential because 802.1X authentication relies on AAA to broker communication with a RADIUS server, which validates endpoint credentials via EAP over RADIUS and returns an Accept or Reject decision that the switch uses to authorize the port. Without AAA and a RADIUS server, the switch lacks an external authentication authority to process 802.1X requests or trigger MAB fallback for non-802.1X endpoints. On the Cisco DCCOR 350-601 exam, this topic tests your understanding of the AAA framework’s role in mixed-access environments, and a common trap is forgetting that 802.1X must be globally enabled—not just on individual interfaces—for MAB fallback to function. Memory tip: think “AAA + RADIUS + global 802.1X” as the three-legged stool that supports both EAP and MAC authentication fallback.
350-601 Security Practice Question
This 350-601 practice question tests your understanding of 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.
Which THREE of the following must be enabled to implement 802.1X authentication with MAB fallback on a Cisco Nexus switch for a mixed environment of 802.1X-capable and non-802.1X endpoints? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
AAA authentication with a RADIUS server
Option B is correct because 802.1X authentication requires AAA to communicate with a RADIUS server. The RADIUS server validates the credentials (EAP over RADIUS) and returns an Accept or Reject, which the switch uses to authorize the port. Without AAA and a RADIUS server, the switch has no external authentication authority to process 802.1X requests or MAB fallback.
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.
✗
MACsec encryption on the port
Why it's wrong here
MACsec is optional and not required for 802.1X/MAB.
✓
AAA authentication with a RADIUS server
Why this is correct
AAA is required to authenticate users and devices.
Related concept
Read the scenario before looking for a memorised answer.
✓
A RADIUS server configured with the MAC addresses of non-802.1X devices
Why this is correct
RADIUS server must have the MAC addresses for MAB authentication.
Related concept
Read the scenario before looking for a memorised answer.
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that MACsec or VLAN ACLs are prerequisites for 802.1X with MAB, when in fact they are optional features that can be layered on top of the authentication process.
Detailed technical explanation
How to think about this question
Under the hood, 802.1X uses EAPoL (EAP over LAN) frames between the supplicant and the authenticator (switch), while the switch encapsulates EAP messages in RADIUS packets (RFC 3579) to communicate with the authentication server. For MAB fallback, the switch sends a RADIUS Access-Request with the MAC address as the username and password (e.g., '00:11:22:33:44:55'), and the RADIUS server must have that MAC pre-configured as a user; if the server responds with Access-Accept, the port is authorized. A real-world scenario is a hospital with IP phones (non-802.1X) and laptops (802.1X) on the same switch, where MAB allows the phones to authenticate using their MAC while laptops use full EAP.
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: AAA authentication with a RADIUS server — Option B is correct because 802.1X authentication requires AAA to communicate with a RADIUS server. The RADIUS server validates the credentials (EAP over RADIUS) and returns an Accept or Reject, which the switch uses to authorize the port. Without AAA and a RADIUS server, the switch has no external authentication authority to process 802.1X requests or MAB fallback.
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.