CCNA 200-125 Exam: CHAP Authentication for PPP Links

CHAP Authentication for PPP Links

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Which value must a device send as its username when using CHAP to authenticate with a remote peer site id:17604704 over a PPP link?



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A. B. C. D.


The correct answer is A. the username defined by the administrator.

Challenge Handshake Authentication Protocol (CHAP) is a PPP authentication protocol that provides protection against replay attacks. CHAP authentication involves a three-way handshake process between two devices, where the device initiating the connection sends a challenge to the remote device, which responds with a value that has been encrypted using a secret key. The initiating device then compares the response with its own calculation of the expected value, and if they match, authentication is successful.

When using CHAP to authenticate with a remote peer site over a PPP link, the device must send the username that has been defined by the administrator. This is because CHAP requires that the same username and secret key be used by both devices in the authentication process. The administrator defines the username and secret key on both devices, and this information must be identical on both devices in order for CHAP authentication to succeed.

Option B, the local hostname, is incorrect because the hostname is not used in CHAP authentication.

Option C, the automatically-generated username, is also incorrect because there is no automatic generation of usernames in CHAP authentication. The username must be explicitly defined by the administrator.

Option D, the hostname of the remote device, is also incorrect because the remote device's hostname is not used in CHAP authentication.