- A
Local AAA authentication uses the username and password configured in the running configuration.
Correct because local authentication relies on the username/password stored on the device.
- B
The 'aaa authentication login default local' command configures the device to use a RADIUS server first, then fall back to local.
Why wrong: Incorrect because this command uses local authentication only; to add fallback, a method list with multiple methods is needed.
- C
When using a RADIUS server group, if the primary server fails to respond, the device automatically tries the next server in the group.
Correct because server groups define an ordered list; if a server is unreachable, the next is tried.
- D
The 'aaa new-model' command is required only when using TACACS+ servers.
Why wrong: Incorrect because 'aaa new-model' is required to enable any AAA functionality, including local, RADIUS, or TACACS+.
- E
Fallback to local authentication occurs only if all remote servers explicitly reject the authentication request.
Why wrong: Incorrect because fallback occurs when servers are unreachable (timeout), not when they reject (which results in denial).
350-401 AAA, RADIUS, and TACACS+ Practice Question
This 350-401 practice question tests your understanding of aaa, radius, and tacacs+. 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 two statements about local AAA and fallback methods are true? (Choose two.)
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
Local AAA authentication uses the username and password configured in the running configuration.
Local AAA uses the device's local database for authentication. Fallback methods define the order of servers to try. If all servers are unreachable, the local database can be used as a backup. The 'aaa authentication login default local' command uses the local database only. The 'aaa new-model' command enables AAA globally.
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.
- ✓
Local AAA authentication uses the username and password configured in the running configuration.
Why this is correct
Correct because local authentication relies on the username/password stored on the device.
Related concept
Authentication checks who the user is.
- ✗
The 'aaa authentication login default local' command configures the device to use a RADIUS server first, then fall back to local.
Why it's wrong here
Incorrect because this command uses local authentication only; to add fallback, a method list with multiple methods is needed.
- ✓
When using a RADIUS server group, if the primary server fails to respond, the device automatically tries the next server in the group.
Why this is correct
Correct because server groups define an ordered list; if a server is unreachable, the next is tried.
Related concept
Authentication checks who the user is.
- ✗
The 'aaa new-model' command is required only when using TACACS+ servers.
- ✗
Fallback to local authentication occurs only if all remote servers explicitly reject the authentication request.
Why it's wrong here
Incorrect because fallback occurs when servers are unreachable (timeout), not when they reject (which results in denial).
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 this command uses local authentication only; to add fallback, a method list with multiple methods is needed.
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 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.
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: Local AAA authentication uses the username and password configured in the running configuration. — Local AAA uses the device's local database for authentication. Fallback methods define the order of servers to try. If all servers are unreachable, the local database can be used as a backup. The 'aaa authentication login default local' command uses the local database only. The 'aaa new-model' command enables AAA globally.
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.
What is the key concept behind this question?
Authentication checks who the user is.
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Last reviewed: Jun 18, 2026
This 350-401 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 350-401 exam.
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