When 802.1X is configured with server-fail fallback on a Juniper EX Series switch and the RADIUS server becomes unavailable, the switch's behavior is twofold. First, for clients that are already authenticated, their sessions are not immediately terminated. They remain connected and can continue to pass traffic until their session timer expires and a re-authentication attempt is required. Second, for any new clients attempting to connect, the fallback mechanism is triggered. Since the vlan-name feature is specified, these new clients are automatically placed into the configured fallback VLAN and granted network access within that segment.

A. An outage of the RADIUS server does not trigger an immediate disconnection of currently authenticated clients; their sessions remain active until re-authentication is attempted.

C. The client does not "request" a VLAN in this context. The switch enforces the configured fallback VLAN for all new clients, regardless of any client-side settings.

1. Juniper Networks TechLibrary, Junos OS Documentation, "Understanding 802.1X Server Fail Fallback":

"If the RADIUS servers are unavailable, supplicants that are already authenticated on the port are not affected. These supplicants remain connected to the LAN." (This supports option B and refutes option A).

"When the RADIUS authentication server is unavailable... you can configure the switch to provide supplicants with access to a limited network or to a specific VLAN." (This supports option D).

2. Juniper Networks TechLibrary, Junos OS Documentation, "Configuring 802.1X Server Fail Fallback (CLI Procedure)":

Under the server-fail hierarchy level, the vlan-name option is described as: "Specifies the VLAN to which the supplicant is moved if the RADIUS server is unavailable." (This directly supports the action described in option D).