The answer is that the console line is missing the 'login authentication default' command. This is correct because, on Cisco IOS, the global 'aaa authentication login default local' method only applies to lines that explicitly reference it; the console line, by default, does not inherit AAA authentication settings. Without the 'login authentication default' command applied under line console 0, the router falls back to its default console authentication behavior, which typically requires no login or uses the local line password, not the AAA local database. On the CCNP ENARSI 300-410 exam, this scenario tests your understanding of how AAA authentication interacts with line-level configuration—a common trap is assuming that the global default automatically applies to all lines, including the console. A helpful memory tip: think of the console as a VIP line that needs a direct invitation; you must explicitly tell it to "login authentication default" to join the AAA party.
300-410 Device Access Control Practice Question
This 300-410 practice question tests your understanding of device access control. 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 engineer configures a Cisco router with 'aaa authentication login default local' and 'aaa authorization exec default local'. The engineer then attempts to log in via the console and is prompted for a username and password. The username 'admin' with password 'cisco' is configured locally. The login fails. 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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The console line is not configured with 'login authentication default'.
Option A is correct because, by default, the console line does not inherit the AAA authentication methods defined under 'aaa authentication login default local'. The 'login authentication default' command must be explicitly applied to the console line under line configuration to use the global AAA authentication method. Without it, the console line falls back to its default behavior, which does not use AAA, causing the login to fail despite the local user being configured.
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.
✓
The console line is not configured with 'login authentication default'.
Why this is correct
Correct because the default AAA login method list must be applied to the console line using the 'login authentication' command.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The username 'admin' is not in the local database.
Why it's wrong here
Incorrect because the username is configured; the failure is due to the method list not being applied.
✗
The password 'cisco' is incorrect.
Why it's wrong here
Incorrect because the scenario states the password is configured correctly.
✗
The 'aaa new-model' command is missing.
Why it's wrong here
Incorrect because if 'aaa new-model' were missing, the AAA commands would not be accepted; the configuration exists.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between defining a default AAA method list and applying it to a specific line, trapping candidates who assume that 'aaa authentication login default local' automatically applies to the console without the 'login authentication default' command.
Trap categories for this question
Command / output trap
Incorrect because if 'aaa new-model' were missing, the AAA commands would not be accepted; the configuration exists.
Scenario analysis trap
Incorrect because the scenario states the password is configured correctly.
Detailed technical explanation
How to think about this question
Under the hood, when 'aaa new-model' is enabled, all lines (console, vty, aux) default to using AAA for authentication unless overridden. However, the console line specifically requires the 'login authentication default' command to bind the global AAA method; otherwise, it uses the legacy 'login' and 'password' commands. This is a common misconfiguration because engineers assume the 'default' keyword applies globally to all lines, but it only defines the method list—the line must still reference it. In real-world scenarios, this often leads to lockouts when AAA servers are unreachable, as the console may not fall back to local authentication without explicit configuration.
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 300-410 question in full detail.
Device Access Control — This question tests Device Access Control — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The console line is not configured with 'login authentication default'. — Option A is correct because, by default, the console line does not inherit the AAA authentication methods defined under 'aaa authentication login default local'. The 'login authentication default' command must be explicitly applied to the console line under line configuration to use the global AAA authentication method. Without it, the console line falls back to its default behavior, which does not use AAA, causing the login to fail despite the local user being configured.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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