- A
The switch port must be configured as an access port and the command 'authentication port-control auto' must be applied.
This is correct because 802.1X requires the port to be an access port and the 'auto' setting places the port in the unauthorized state initially, triggering the authentication process.
- B
AAA authentication for 802.1X must be configured using TACACS+ as the protocol of choice.
Why wrong: TACACS+ is used for device administration (e.g., login, exec authorization), not for 802.1X. 802.1X relies on RADIUS for authentication.
- C
The global command 'aaa new-model' is sufficient to enable 802.1X on all interfaces.
Why wrong: While 'aaa new-model' is required to enable AAA services globally, it alone does not enable 802.1X. Additional commands like 'dot1x system-auth-control' and interface-specific configurations are needed.
- D
RADIUS is the recommended protocol for 802.1X authentication because it supports EAP and is widely used in network access control.
RADIUS is the standard for 802.1X because it can encapsulate EAP messages and is designed for network access authentication, making it the correct choice.
- E
802.1X can be configured on a trunk port to authenticate multiple VLANs simultaneously.
Why wrong: 802.1X is designed for access ports, not trunk ports. While there are advanced features like multi-domain authentication, the standard configuration requires an access port. Trunk ports are not supported for 802.1X in typical implementations.
Quick Answer
The correct answer identifies RADIUS as the recommended protocol for 802.1X port authentication because it natively supports EAP extensions, which are essential for secure network access control, while TACACS+ lacks EAP support and is better suited for device administration. On Cisco IOS-XE, configuring 802.1X with AAA and RADIUS requires the switch port to be set as an access port with the `authentication port-control auto` command to enable EAPoL-based authentication, and the `aaa new-model` command alone is insufficient—you must also issue `dot1x system-auth-control` globally and apply per-interface settings. On the CCNA 200-301 v2 exam, this topic tests your ability to distinguish between RADIUS and TACACS+ roles, with a common trap being the assumption that TACACS+ can handle 802.1X or that trunk ports support it. Remember the memory tip: “RADIUS for access, TACACS+ for admin—EAP only rides on RADIUS tracks.”
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. 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.
Which TWO statements correctly describe the configuration and verification of AAA with RADIUS/TACACS+ and 802.1X port-based authentication on IOS-XE?
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 switch port must be configured as an access port and the command 'authentication port-control auto' must be applied.
Option A is correct because 802.1X requires the switch port to be an access port (not trunk or dynamic) and the 'authentication port-control auto' command enables EAPoL-based authentication. Option D is correct because RADIUS is the recommended protocol for 802.1X; it natively supports EAP extensions and is widely used for network access control, whereas TACACS+ does not support EAP and is more suited for device administration. Option B is false because AAA authentication for 802.1X should use RADIUS, not TACACS+. Option C is false because 'aaa new-model' only activates the AAA framework; 802.1X requires additional global commands like 'dot1x system-auth-control' and per-interface configuration. Option E is false because 802.1X is typically configured on access ports and cannot be used on trunk ports to authenticate multiple VLANs; the port must be in access mode.
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 switch port must be configured as an access port and the command 'authentication port-control auto' must be applied.
Why this is correct
This is correct because 802.1X requires the port to be an access port and the 'auto' setting places the port in the unauthorized state initially, triggering the authentication process.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
AAA authentication for 802.1X must be configured using TACACS+ as the protocol of choice.
- ✗
The global command 'aaa new-model' is sufficient to enable 802.1X on all interfaces.
- ✓
RADIUS is the recommended protocol for 802.1X authentication because it supports EAP and is widely used in network access control.
- ✗
802.1X can be configured on a trunk port to authenticate multiple VLANs simultaneously.
Why it's wrong here
802.1X is designed for access ports, not trunk ports. While there are advanced features like multi-domain authentication, the standard configuration requires an access port. Trunk ports are not supported for 802.1X in typical implementations.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The switch port must be configured as an access port and the command 'authentication port-control auto' must be applied.Correct answer▾
Why this is correct
This is correct because 802.1X requires the port to be an access port and the 'auto' setting places the port in the unauthorized state initially, triggering the authentication process.
✗AAA authentication for 802.1X must be configured using TACACS+ as the protocol of choice.Wrong answer — click to see why▾
Why this is wrong here
TACACS+ does not support the EAP (Extensible Authentication Protocol) frames needed for 802.1X; RADIUS is the required protocol.
✗The global command 'aaa new-model' is sufficient to enable 802.1X on all interfaces.Wrong answer — click to see why▾
Why this is wrong here
Without 'dot1x system-auth-control' and per-interface authentication settings, 802.1X will not operate.
✗802.1X can be configured on a trunk port to authenticate multiple VLANs simultaneously.Wrong answer — click to see why▾
Why this is wrong here
Trunk ports carry multiple VLANs and do not support the port-based authentication model of 802.1X without special configurations that are not part of the standard CCNA scope.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that 'aaa new-model' alone enables all AAA features, including 802.1X, when in fact it only activates the AAA framework and separate interface-level commands are required.
Trap categories for this question
Command / output trap
While 'aaa new-model' is required to enable AAA services globally, it alone does not enable 802.1X. Additional commands like 'dot1x system-auth-control' and interface-specific configurations are needed.
Detailed technical explanation
How to think about this question
Under the hood, 802.1X uses EAP over LAN (EAPoL) between the supplicant and authenticator (switch), and the switch encapsulates EAP messages in RADIUS (RFC 3579) to communicate with the authentication server. A common real-world scenario is deploying 802.1X on a campus network where the switch must be in 'auto' mode to force authentication before granting network access; misconfiguring the port as a trunk or dynamic desirable will cause authentication to fail or be bypassed.
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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
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FAQ
Questions learners often ask
What does this 200-301 question test?
Network Services and Security — This question tests Network Services and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The switch port must be configured as an access port and the command 'authentication port-control auto' must be applied. — Option A is correct because 802.1X requires the switch port to be an access port (not trunk or dynamic) and the 'authentication port-control auto' command enables EAPoL-based authentication. Option D is correct because RADIUS is the recommended protocol for 802.1X; it natively supports EAP extensions and is widely used for network access control, whereas TACACS+ does not support EAP and is more suited for device administration. Option B is false because AAA authentication for 802.1X should use RADIUS, not TACACS+. Option C is false because 'aaa new-model' only activates the AAA framework; 802.1X requires additional global commands like 'dot1x system-auth-control' and per-interface configuration. Option E is false because 802.1X is typically configured on access ports and cannot be used on trunk ports to authenticate multiple VLANs; the port must be in access mode.
What should I do if I get this 200-301 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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Last reviewed: Jun 11, 2026
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