In a WLAN network using Agile Controller as an admission controller, which of the following options is not the cause of 802.1x authentication failure?

Question

Options

• AThe key of the Agile Controller access device is inconsistent with the key configured on the device
• BThe billing cycle is not configured
• CPort 1813 on the server is occupied
• DAuthorization rule matching is to deny access

• A
  4% (1)
• B
  81% (22)
• C
  4% (1)
• D
  11% (3)

Explanation

Option B is correct because the billing cycle is a post-authentication accounting/billing configuration - it governs how usage is measured and charged after a user is already connected, and has no role in the 802.1x authentication handshake itself. Leaving it unconfigured does not prevent a user from being authenticated.

Why the distractors are genuine failure causes:

• (A) The shared secret (key) between the Agile Controller RADIUS server and the network access device must match exactly; a mismatch causes RADIUS messages to be rejected, directly breaking 802.1x.
• (C) Port 1813 is the RADIUS Accounting port; if it is occupied, the RADIUS service may fail to start entirely, taking down authentication (port 1812) along with it.
• (D) If an authorization rule explicitly denies access, the RADIUS server returns an Access-Reject, terminating the authentication process regardless of whether credentials were valid.

Memory tip: Think of 802.1x as a two-phase process - authenticate first, then account. Billing/accounting settings (including billing cycles) belong to the second phase; they can only run after authentication succeeds, so they can never be the reason authentication fails in the first place.

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