350-601 Security Practice Question
Exhibit
Refer to the exhibit. ! Output from show running-config | section security ! feature tacacs+ tacacs-server host 10.1.1.1 key ciscosecret tacacs-server directed-request aaa authentication login default group tacacs+ local aaa authentication enable default group tacacs+ local aaa authorization commands default group tacacs+ local aaa accounting commands default group tacacs+
Refer to the exhibit. The TACACS+ server at 10.1.1.1 is unreachable. What will happen when a user tries to authenticate to the switch using SSH?
⚠ Common exam trap
Cisco often tests the misconception that 'fallback-to-local' must be explicitly configured for TACACS+ fallback to work, when in reality the fallback is determined by the order of methods in the AAA authentication command, and 'local' as a subsequent method provides the fallback automatically.
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
✓
Authentication will use the local user database as a fallback.
When the TACACS+ server at 10.1.1.1 is unreachable, the switch will fall back to the local user database for authentication because the 'fallback-to-local' feature is enabled by default in Cisco IOS/IOS-XE for TACACS+ configurations. This behavior ensures that administrative access is not completely blocked if the remote AAA server becomes unavailable, allowing authentication against locally configured usernames and passwords.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Authentication will use the local user database as a fallback.
Why this is correct
The 'local' keyword provides fallback.
- ✗
Authentication will be denied immediately.
Why it's wrong here
There is a fallback to local authentication.
- ✗
Authentication will be attempted against the TACACS+ server repeatedly until timeout.
Why it's wrong here
It will fallback to local after the first attempt.
- ✗
Authentication will be attempted against the TACACS+ server without fallback because 'fallback-to-local' is not configured.
Why it's wrong here
The 'local' keyword enables fallback.
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-601 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 350-601 exam.