Exam JN0-648 topic 1 question 30 discussion

single supplicant—Authenticates only the first end device. All other end devices that connect later to the port are allowed full access without any further authentication. They effectively piggyback on the first end device’s authentication. single-secure supplicant—Allows only one end device to connect to the port. No other end device is allowed to connect until the first device logs out. multiple supplicant—Allows multiple end devices to connect to the port. Each end device is authenticated individually. https://www.juniper.net/documentation/en_US/junos/topics/topic-map/802-1x-authentication-switching-devices.html

imho - single supplicant mode VoIP VLAN—Supports IP telephones. The implementation of a voice VLAN on an IP telephone is vendor-specific. If the phone is 802.1X-enabled, it is authenticated as any other supplicant is. If the phone is not 802.1X-enabled, but has another 802.1X-compatible device connected to its data port, that device is authenticated, and then VoIP traffic can flow to and from the phone (provided that the interface is configured in single supplicant mode and not in single-secure supplicant mode).

Multiple. https://www.juniper.net/documentation/us/en/software/junos/user-access/topics/topic-map/802-1x-authentication-switching-devices.html