Cisco Certified Network Professional Practice Test 2025 – Your All-in-One Guide to Exam Success!

TACACS+ is an authentication method that stands out because it provides a robust mechanism for validating user credentials against one or multiple centralized authentication servers. When a user attempts to access a network device, TACACS+ checks the credentials against all configured TACACS+ servers in a sequence until a successful authentication is achieved or all servers have been checked. This is beneficial for ensuring that the authentication process is thorough and reliable, especially in environments with multiple servers for redundancy or load balancing.

In contrast, local authentication typically relies on credentials stored directly on the device, meaning it doesn't reach out to any external servers. Line authentication often deals with access to specific console or vty lines but doesn't encompass broader server checks. RADIUS, while it can check against remote servers, does not support the same level of server querying as TACACS+, as RADIUS typically uses only the first server that responds, which may not be comprehensive in scenarios with multiple available authentication servers. Thus, TACACS+ is specifically designed to check all configured servers, making it the correct answer to this question.