What is the maximum data rate specified for IEEE 802.11b WLANs?（）

A.任何到达一个和路由器R1非直连的网络的数据包都会被丢弃
B.任何到达一个和路由器R2非直连的网络的数据包都会被丢弃
C.任何到达一个和路由器R2非直连的网络的数据包都会即时被丢弃，因为R1上缺少网关
D.直连在R2上的网络将不能够和172.16.100.0，172.16.100.128，172.16.100.64这些子网通讯
E.任何目的地没有在R2的路由表中的数据包，R2将会定向到R1，R1会发送哪个数据包到R2，这样路由环路产生

A.spanning-tree mode rapid-pvst
B.spanning-tree uplinkfast
C.spanning-tree backbonefast
D.spanning-tree mode mst

A.to prevent unauthorized Telnet access to a switch port
B.to limit the number of Layer 2 broadcasts on a particular switch port
C.to prevent unauthorized hosts from accessing the LAN
D.to protect the IP and MAC address of the switch and associated ports
E.to block unauthorized access to the switch management interfaces over common TCP ports