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