There is an AS-path-filter, ip as-path-filter 1 permit ^100(_100)*(_400)*, which AS-PATH attribute cannot be matched by the As-path-filter?

Cross-device link aggregation enables data stream transmission and mutual backup of stack member switches. However, because of the limited bandwidth of stack cables between stack devices, which of the following methods can improve forwarding efficiency?

For Layer 2 VPN technology, which of the following statements are correct? (Multiple Choice)

If the PPP link between R1 and R2 is shown, and the direct connection port is not on the same network segment, but the R1 and R2 direct connection ports can communicate, and the Ethernet link cannot communicate under the same IP planning, what is the reason? (Multiple choice)

Two routers are connected through the serial port, but the interconnection interface cannot be pinged. Now check the port status as follows, which is the possible reason?  (No figure is shown, one PPP, and one HDLC, you can find the reason.)