Which protocol is an open standard protocol framework that is commonly used in VPNs,to provid secure end-to-end communication?（）

A. PVST+reduces the CPU cycles for all the switches in the network
B. PVST+automatically selects the root bridge location,to provide optimized bandwidth usage.
C. PVST+allow the root switch location to be optimized per vlan.
D. PVST+supports Layer 3 load balancing without loops.

A. access-list 50 deny 192.168.1.1 0.0.0.255
B. access-list 110 permit ip any any
C. access-list 2500 deny tcp any host 192.168.1.1 eq 22
D. access-list 101 deny tcp any host 192.168.1.1

A. you can apply multiple access lists with the same protocol or in different direction.
B. you can config one access list,per direction,per layer 3 protocol
C. you can place as many access lists as you want on any interface
D. you can apply only one access list on any interface