- A
The switch interface is configured as a static access port, which overrides the RADIUS-supplied VLAN.
Correct because if the interface has a static 'switchport access vlan' command, it takes precedence over the RADIUS-assigned VLAN. The interface should be configured as 'switchport access vlan dynamic' or have no static VLAN assignment to allow RADIUS to assign the VLAN.
- B
The RADIUS server is sending the VLAN ID as a number, but the switch expects a VLAN name.
Why wrong: Incorrect because the 'Tunnel-Private-Group-ID' attribute can carry either a VLAN ID or name; the switch can handle both if the VLAN exists.
- C
The switch needs the 'radius-server attribute 8 include-in-access-req' command to include the calling station ID.
Why wrong: Incorrect because that command is for including attributes in requests, not for processing VLAN assignment responses.
- D
The switch's VLAN database does not have the VLAN created, so it defaults to the native VLAN.
Why wrong: Incorrect because the scenario states the VLAN is defined on the switch, so that is not the issue.
Quick Answer
The answer is that the switch interface is configured as a static access port, which overrides the RADIUS-supplied VLAN. Even though the Cisco ISE sends the correct Tunnel-Private-Group-ID attribute and the switch has the VLAN defined, a static access port assignment takes precedence over dynamic VLAN assignment from RADIUS. For the switch to honor the RADIUS VLAN, the interface must be set to dynamic mode using the `switchport access vlan dynamic` command, or the port must be configured with `authentication` commands that allow VLAN assignment. On the ENCOR 350-401 exam, this tests your understanding of how 802.1X authorization interacts with switchport configuration—a common trap is assuming that `aaa authorization network default group radius` alone is sufficient. Remember: static access always beats dynamic RADIUS VLANs. Memory tip: “Static sticks, dynamic dips”—if the port is statically assigned, the dynamic VLAN from ISE gets ignored.
350-401 AAA, RADIUS, and TACACS+ Practice Question
This 350-401 practice question tests your understanding of aaa, radius, and tacacs+. 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 uses a Cisco ISE as the RADIUS server for both wired and wireless authentication. The network engineer configures a Cisco switch with 'aaa authentication dot1x default group radius' and 'aaa authorization network default group radius'. When a user connects via 802.1X, authentication succeeds, but the user is placed in the wrong VLAN. The RADIUS server sends a 'Tunnel-Private-Group-ID' attribute with the correct VLAN name. The switch has the VLAN defined. 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.
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
The switch interface is configured as a static access port, which overrides the RADIUS-supplied VLAN.
The switch must be configured to accept and apply RADIUS-supplied VLAN attributes. This requires the 'aaa authorization network default group radius' command, which is already configured. However, the switch may also need the 'radius-server attribute 6 on-for-login-auth' or similar to map the attribute to a VLAN. But the most common issue is that the switch's interface is not configured for 'authentication port-control auto' or the VLAN is not in the allowed list. However, the scenario says authentication succeeds, so the port is authorized. The likely cause is that the switch is not configured to use the RADIUS-supplied VLAN because the interface is not set to 'switchport access vlan dynamic' or the 'authentication' command is missing the 'vlan' assignment.
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 interface is configured as a static access port, which overrides the RADIUS-supplied VLAN.
Why this is correct
Correct because if the interface has a static 'switchport access vlan' command, it takes precedence over the RADIUS-assigned VLAN. The interface should be configured as 'switchport access vlan dynamic' or have no static VLAN assignment to allow RADIUS to assign the VLAN.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Authentication checks who the user is.
- ✗
The RADIUS server is sending the VLAN ID as a number, but the switch expects a VLAN name.
Why it's wrong here
Incorrect because the 'Tunnel-Private-Group-ID' attribute can carry either a VLAN ID or name; the switch can handle both if the VLAN exists.
- ✗
The switch needs the 'radius-server attribute 8 include-in-access-req' command to include the calling station ID.
Why it's wrong here
Incorrect because that command is for including attributes in requests, not for processing VLAN assignment responses.
- ✗
The switch's VLAN database does not have the VLAN created, so it defaults to the native VLAN.
Why it's wrong here
Incorrect because the scenario states the VLAN is defined on the switch, so that is not the issue.
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.
Trap categories for this question
Command / output trap
Incorrect because that command is for including attributes in requests, not for processing VLAN assignment responses.
Scenario analysis trap
Incorrect because the scenario states the VLAN is defined on the switch, so that is not the issue.
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 350-401 questions on access control and AAA configuration.
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FAQ
Questions learners often ask
What does this 350-401 question test?
AAA, RADIUS, and TACACS+ — This question tests AAA, RADIUS, and TACACS+ — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: The switch interface is configured as a static access port, which overrides the RADIUS-supplied VLAN. — The switch must be configured to accept and apply RADIUS-supplied VLAN attributes. This requires the 'aaa authorization network default group radius' command, which is already configured. However, the switch may also need the 'radius-server attribute 6 on-for-login-auth' or similar to map the attribute to a VLAN. But the most common issue is that the switch's interface is not configured for 'authentication port-control auto' or the VLAN is not in the allowed list. However, the scenario says authentication succeeds, so the port is authorized. The likely cause is that the switch is not configured to use the RADIUS-supplied VLAN because the interface is not set to 'switchport access vlan dynamic' or the 'authentication' command is missing the 'vlan' assignment.
What should I do if I get this 350-401 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 350-401 questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". 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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Last reviewed: Jun 18, 2026
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