A.protecting a server frome unauthorized acces
B.controlling path selection，based on the route metric
C.reducing router CPU utilization
D.filterring packets that are passing through a router

A.Enable VTP pruning
B.From privileged mode，erase the startup configuration file，then reload.
C.From privileged mode，erase the vlandate file，then reload.
D.Cycle the switch power.

A.点到点
B.广播多路访问
C.非广播多路访问
D.非广播多点
E.广播点到多点

A.It designates VLAN 999 for untagged traffic.
B.It blocks VLAN 999 traffic from passing on the trunk.
C.It createsa VLAN 999 interface.
D.It designates VLAN 999 as the default for all unkown tagged traffic.

A.complicated header
B.plug-and-play
C.no broadcasts
D.checksums
E.optional IPsec
F.autoconfiguration

A.FE08：：280e：611：a：f14f：3d69
B.FE81：：280f：512b：e14f：3d69
C.FE80：：380e：611a：e14f：3d69
D.FEFE：0345：5f1b：：e14d：3d69

A.They are always present in the NATt able.
B.They allow connection to be initiated from the outside.
C.They can be configured with access lists，to allow two or more connections to be initiated from the outside.
D.They require no inside or outside interface markings because addresses are statically defined.

A.AH
B.MB5
C.PSK
D.ESP

A.ipv6 address PREFIX_1::1/64
B.ipv6 autoconfig 2001:db8:2222:7272::72/64
C.ipv6 autoconfig
D.ipv6 address 2001:db8:2222:7272::72/64

A.A
B.B
C.C
D.D
E.E
F.F

A.4094
B.1024
C.8190
D.2046
E.4096