The answer is that users can still log in using local credentials if the TACACS+ server becomes unreachable. This behavior occurs because the configuration includes the `aaa authentication login default group tacacs+ local` command, which explicitly specifies `local` as a fallback method. When the TACACS+ server is unreachable, the switch automatically reverts to the local database for authentication, allowing users to authenticate with locally stored usernames and passwords. On the Cisco CyberOps Associate 200-201 exam, this concept tests your understanding of AAA fallback mechanisms and the critical difference between authentication lists that include `local` versus those that do not—a common trap is assuming that a missing `local` keyword still permits fallback, which is incorrect. Remember the memory tip: “No local, no login” if the server goes down; the `local` keyword is your safety net for TACACS+ fallback to local authentication.
200-201 Security Policies and Procedures Practice Question
This 200-201 practice question tests your understanding of security policies and procedures. 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.
Exhibit
Refer to the exhibit.
```
switch# show running-config | include aaa
aaa new-model
aaa authentication login default local
aaa authorization exec default local
aaa accounting exec default start-stop group tacacs+
```
Refer to the exhibit. A network administrator is configuring TACACS+ on a switch. Based on the configuration snippet, what is the expected behavior if the TACACS+ server becomes unreachable?
Refer to the exhibit.
```
switch# show running-config | include aaa
aaa new-model
aaa authentication login default local
aaa authorization exec default local
aaa accounting exec default start-stop group tacacs+
```
A
Users cannot log in because TACACS+ is required.
Why wrong: Although TACACS+ is used for accounting, authentication is configured as local.
B
Users can still log in using local credentials.
The command 'aaa authentication login default local' specifies that local authentication is used by default.
C
Users can log in but accounting logs are not generated.
Why wrong: Accounting will fail if TACACS+ is unreachable, but authentication still works.
D
The switch falls back to no authentication.
Why wrong: Local authentication is explicitly configured.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Users can still log in using local credentials.
The configuration snippet shows the 'tacacs-server host' command but does not include the 'tacacs-server directed-request' or 'aaa authentication login default group tacacs+ local' statement. By default, when 'aaa authentication login default group tacacs+' is configured without the 'local' fallback method, the switch will use local authentication if the TACACS+ server is unreachable. Option B is correct because the switch is configured to fall back to local credentials when the TACACS+ server becomes unreachable, as indicated by the presence of 'local' in the authentication list.
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.
✗
Users cannot log in because TACACS+ is required.
Why it's wrong here
Although TACACS+ is used for accounting, authentication is configured as local.
✓
Users can still log in using local credentials.
Why this is correct
The command 'aaa authentication login default local' specifies that local authentication is used by default.
Related concept
Read the scenario before looking for a memorised answer.
✗
Users can log in but accounting logs are not generated.
Why it's wrong here
Accounting will fail if TACACS+ is unreachable, but authentication still works.
✗
The switch falls back to no authentication.
Why it's wrong here
Local authentication is explicitly configured.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between 'authentication failure' (server reachable but rejects credentials) and 'server unreachable' (no response), where fallback to local only occurs in the latter case when 'local' is explicitly configured as a secondary method.
Detailed technical explanation
How to think about this question
Under the hood, Cisco IOS uses the 'aaa authentication login default' command to define the authentication method list; the order of methods matters—'group tacacs+' is tried first, and if the server is unreachable (not just authentication failure), the switch moves to the next method ('local'). A subtle behavior is that if the TACACS+ server is reachable but returns a 'deny' response, the switch does not fall back to local; fallback only occurs on server unreachability (timeout or no response). In real-world scenarios, this prevents lockout during network outages while maintaining security through local accounts.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security Policies and Procedures — This question tests Security Policies and Procedures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Users can still log in using local credentials. — The configuration snippet shows the 'tacacs-server host' command but does not include the 'tacacs-server directed-request' or 'aaa authentication login default group tacacs+ local' statement. By default, when 'aaa authentication login default group tacacs+' is configured without the 'local' fallback method, the switch will use local authentication if the TACACS+ server is unreachable. Option B is correct because the switch is configured to fall back to local credentials when the TACACS+ server becomes unreachable, as indicated by the presence of 'local' in the authentication list.
What should I do if I get this 200-201 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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