The answer is the interface configuration command authentication port-control auto. This command is correct because it places the switch port into an unauthorized state by default, forcing the connected client to authenticate via 802.1X before gaining network access; only after successful authentication with the RADIUS server—such as Cisco ISE—does the port transition to an authorized state. On the ENCOR 350-401 exam, this concept tests your understanding of the three port-control modes (force-authorized, force-unauthorized, and auto), with auto being the only mode that actively enforces the 802.1X authentication process. A common trap is confusing force-authorized (which bypasses authentication) with auto, or thinking that RADIUS configuration alone is sufficient—without authentication port-control auto on the switch interfaces, the port remains open and 802.1X is never triggered. Remember the memory tip: "Auto starts the auth—without it, the port is just a door with no lock."
350-401 Security Practice Question
This 350-401 practice question tests your understanding of 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.
An organization wants to implement 802.1X authentication on its wired network using Cisco ISE as the authentication server. The switches are configured with the necessary RADIUS settings. Which additional configuration is required on the switch interfaces to enable 802.1X?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
authentication port-control auto
Option B is correct because 'authentication port-control auto' is the required interface command to enable 802.1X authentication on a switch port. This command sets the port to initiate the authentication process, placing it in the unauthorized state until the client successfully authenticates via the RADIUS server (Cisco ISE). Without this command, the port will not enforce 802.1X.
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.
✗
dot1x pae authenticator
Why it's wrong here
This command is needed but only enables the PAE role; 'authentication port-control auto' is also required.
✓
authentication port-control auto
Why this is correct
Correct: this command enables 802.1X authentication on the interface.
Related concept
Read the scenario before looking for a memorised answer.
✗
authentication port-control force-authorized
Why it's wrong here
This command disables 802.1X and sets the port to authorized state.
✗
authentication port-control force-unauthorized
Why it's wrong here
This command forces the port to unauthorized state, blocking all traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between the 'dot1x pae authenticator' command and the 'authentication port-control auto' command, leading candidates to mistakenly think the PAE command alone enables 802.1X, when in fact both are required for full functionality.
Trap categories for this question
Command / output trap
This command is needed but only enables the PAE role; 'authentication port-control auto' is also required.
Detailed technical explanation
How to think about this question
Under the hood, the 'authentication port-control auto' command triggers the switch to act as an 802.1X authenticator, sending EAP-Request/Identity frames to the supplicant and relaying EAP messages to the RADIUS server (ISE). A subtle behavior is that this command also enables MAC Authentication Bypass (MAB) as a fallback if the client does not support 802.1X, which is critical in mixed environments. In real-world deployments, forgetting this command is a common misconfiguration that leaves ports open or non-functional.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
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 port-control auto — Option B is correct because 'authentication port-control auto' is the required interface command to enable 802.1X authentication on a switch port. This command sets the port to initiate the authentication process, placing it in the unauthorized state until the client successfully authenticates via the RADIUS server (Cisco ISE). Without this command, the port will not enforce 802.1X.
What should I do if I get this 350-401 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.
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Question Discussion
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