单选题Which statement is correct about logical units on Juniper Router interfaces?（）A Logical units are used only when a Layer 2 identifier is present such as a VLANB A logical unit of 0 is required when using a frame-relay DLCIC A logical unit is always req
题目
单选题
Which statement is correct about logical units on Juniper Router interfaces?（）
A
Logical units are used only when a Layer 2 identifier is present such as a VLAN
B
A logical unit of 0 is required when using a frame-relay DLCI
C
A logical unit is always required
D
Logical units are not required unless ATM or 802.1Q VLAN tagging is configured.