hardMultiple Select
350-401 Practice Question: Which three statements about configuring AAA on…
Which three statements about configuring AAA on Cisco IOS devices are true? (Choose three.)
⚠ Common exam trap
The trap here is mixing up the commands for RADIUS and TACACS+ servers, or thinking aaa new-model disables local authentication; candidates might also forget that method lists are required for specific authentication methods.
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 aaa new-model command enables AAA services on the device.
Option A is correct because the aaa new-model command is the global configuration command that enables the AAA access-control model on a Cisco IOS device, activating authentication, authorization, and accounting functionality. Option C is correct because the radius-server host command specifies a RADIUS server's IP address (or hostname) and can include the shared secret via the key parameter, identifying the server for AAA communication. Option E is correct because the aaa authentication login command creates a named or default method list that defines the sequence of authentication methods (such as local, RADIUS, or TACACS+) applied to login sessions. Option B is incorrect because aaa new-model does not disable local authentication; local authentication remains available as a method within a method list, and external servers are only used if configured in that list. Option D is incorrect because the tacacs-server host command configures a TACACS+ server, not a RADIUS server, and the shared secret is typically set with the tacacs-server key command.
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 aaa new-model command enables AAA services on the device.
Why this is correct
The aaa new-model command activates the AAA subsystem, after which authentication, authorisation and accounting methods can be defined and applied to lines and interfaces. Without it, the device ignores those method lists, so this command is the prerequisite for any AAA configuration.
- ✗
The aaa new-model command disables local authentication and forces the use of an external server.
Why it's wrong here
The `aaa new-model` command does not disable local authentication; it enables the AAA framework, after which local fallback remains available via `aaa authentication login default local`. It is tempting because enabling new-model does override the legacy `line`/`login local` behaviour, so it would be the right answer if the statement claimed it changes default authentication methods rather than removing local authentication entirely.
- ✓
The radius-server host command is used to specify the IP address and shared secret for a RADIUS server.
Why this is correct
The radius-server host command defines the RADIUS server's address together with its shared secret, which the router uses to authenticate and encrypt exchanges with that server. This satisfies the stem's requirement for specifying server address and key.
- ✗
The tacacs-server host command is used to specify the IP address and shared secret for a RADIUS server.
Why it's wrong here
The tacacs-server host command configures TACACS+ servers, not RADIUS; RADIUS uses the radius-server host command with its own key syntax. It is tempting because both commands specify host address and shared secret, but the protocol and default port differ, so this statement is false.
- ✓
The aaa authentication login command defines a method list for login authentication.
Why this is correct
The aaa authentication login command creates named method lists that specify which authentication methods (such as local, TACACS+, or RADIUS) are tried, and in what order, when a user attempts to log in. This directly satisfies the requirement to define login authentication behaviour on Cisco IOS devices.
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.
Go deeper
Related to this question
Learn chapter
SDN Controllers and Cisco ACI
Key term
RADIUS vs TACACS+
RADIUS and TACACS+ are two network protocols used to verify user identities and control access to network devices and services, with different approaches to security and flexibility.
Key term
AAA on Cisco Devices
AAA on Cisco devices is a security framework that controls who can access the network, what they can do, and keeps a record of their actions.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.