350-401 Question 267
Single answerA network administrator is configuring 802.1X authentication on a Cisco switch to secure access to the network. The switch is configured as an authenticator, and the authentication server is reachable. However, users report that they are unable to authenticate and gain access to the network. Upon review, the administrator notices that the endpoints do not respond to EAP requests from the switch. Which of the following is the MOST likely cause of this issue?
- A
The endpoints do not have a supplicant configured.
- B
The authentication server is not reachable from the switch.
- C
The switch does not have the correct RADIUS server IP address configured.
- D
The endpoints are using an unsupported EAP method.
Show answer and explanation
Correct answer: A
Explanation
In an 802.1X setup, the endpoint plays the role of the supplicant, which is responsible for responding to EAP requests sent by the authenticator (switch). If the supplicant is not configured or enabled on the endpoint, it will not respond to the EAP requests, resulting in authentication failure. The other options involve issues that occur at later stages of the 802.1X authentication process or are unrelated to the described problem.
- A. Correct.
802.1X requires a supplicant (software on the endpoint) to respond to EAP requests from the authenticator (the switch). If the supplicant is not configured or enabled, the endpoint will not respond, leading to authentication failure.
- B. Incorrect.
If the authentication server were unreachable, the switch would still send EAP requests to the endpoints, but authentication would ultimately fail after a timeout. This scenario specifically mentions that endpoints are not responding to EAP requests, which points to a different issue.
- C. Incorrect.
An incorrect RADIUS server IP address would cause authentication failures after the switch forwards EAP messages to the server. However, this scenario indicates that the problem lies in the endpoints not responding to EAP requests, which occurs earlier in the authentication process.
- D. Incorrect.
While using an unsupported EAP method could cause authentication issues, the scenario specifies that the issue is with endpoints not responding to EAP requests, which is unrelated to the EAP method being used.