- A
The router has no local usernames configured, so the 'local' method has no users to authenticate against.
Correct because 'local' authentication uses the local username database; if no usernames are configured, authentication fails.
- B
The 'aaa authentication login CONSOLE local' command should be 'aaa authentication login CONSOLE group radius local' to include RADIUS as a fallback.
Why wrong: Incorrect because the engineer wants only local authentication for console when RADIUS is down; the current configuration is correct for that purpose, but the local database is empty.
- C
The console line should use the default authentication list instead of a named list.
Why wrong: Incorrect because using a named list is fine; the issue is not the list name but the lack of local users.
- D
The 'aaa new-model' command is missing, so AAA is not enabled.
Why wrong: Incorrect because if 'aaa new-model' were missing, the authentication commands would not be accepted; the engineer was able to configure them, so it is present.
Quick Answer
The answer is that no local usernames have been configured on the router. Even though the console line correctly references the CONSOLE method list with only the local method, the AAA fallback to local authentication will fail if the local database is empty. The command `aaa authentication login CONSOLE local` tells the router to use its local user database, but without a `username` command defining credentials, there are no valid accounts to authenticate against. On the ENCOR 350-401 exam, this scenario tests your understanding that AAA method lists define *where* to check, not *what* to check—the local database must be populated. A common trap is assuming that simply specifying `local` is enough, or confusing the `default` list with a named list. Remember the mnemonic: **L**ocal **U**sers **M**ust **E**xist (LUME)—if you specify local, you must first create usernames.
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.
A network engineer is configuring a Cisco router for AAA using a RADIUS server. The engineer wants to ensure that if the RADIUS server is unreachable, the router falls back to local authentication for console access. The engineer configures 'aaa authentication login default group radius local' and 'aaa authentication login CONSOLE local'. The console line is configured with 'login authentication CONSOLE'. However, when the RADIUS server is down, the engineer cannot log in via the console. What is the problem?
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 router has no local usernames configured, so the 'local' method has no users to authenticate against.
The console line is configured to use the 'CONSOLE' method list, which only has 'local' as the method. This is correct for fallback. However, the issue might be that the local database has no users defined, or the 'local' method is not working because the 'username' command is missing. But the scenario says the engineer cannot log in, implying that local authentication is failing. The most likely cause is that no local usernames are configured on the router.
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 router has no local usernames configured, so the 'local' method has no users to authenticate against.
Why this is correct
Correct because 'local' authentication uses the local username database; if no usernames are configured, authentication fails.
Related concept
Authentication checks who the user is.
- ✗
The 'aaa authentication login CONSOLE local' command should be 'aaa authentication login CONSOLE group radius local' to include RADIUS as a fallback.
Why it's wrong here
Incorrect because the engineer wants only local authentication for console when RADIUS is down; the current configuration is correct for that purpose, but the local database is empty.
- ✗
The console line should use the default authentication list instead of a named list.
Why it's wrong here
Incorrect because using a named list is fine; the issue is not the list name but the lack of local users.
- ✗
The 'aaa new-model' command is missing, so AAA is not enabled.
Why it's wrong here
Incorrect because if 'aaa new-model' were missing, the authentication commands would not be accepted; the engineer was able to configure them, so it is present.
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 if 'aaa new-model' were missing, the authentication commands would not be accepted; the engineer was able to configure them, so it is present.
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: The router has no local usernames configured, so the 'local' method has no users to authenticate against. — The console line is configured to use the 'CONSOLE' method list, which only has 'local' as the method. This is correct for fallback. However, the issue might be that the local database has no users defined, or the 'local' method is not working because the 'username' command is missing. But the scenario says the engineer cannot log in, implying that local authentication is failing. The most likely cause is that no local usernames are configured on the router.
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
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