A.Units in JUNOS are always required for any interface configured with logical addresses such as IP and IPv6.
B.Units in JUNOS are only required when you are configuring sub-interfaces for inter-VLAN routing.
C.Unit numbers must match the DLCI or VCI numbers configured on the interface.
D.Unit 0 is the only value allowed on interfaces running HDLC, PPP, or for Ethernet interfaces not doing VLAN-tagging.
参考答案：AD
