单项选择题 A company has a small network，consisting of a single switch and a single router. The switch has been configured with two vlans，and route-on-a-stick is being configured on the router for inter-vlan routing. A trunk is configured to connect the switch to the router.What is the minimum number of router subinterfaces that are required for all the vlans to communicate？（）

多项选择题 What can a network administrator utilize by using PPP Layer 2 encapsulation (Choose three.) （）。

单项选择题 网络管理员在交换机1上创建一个新VLAN并且将主机C和主机D加入到此VLAN中。管理员配置交换机接口FastEthernet0/13到FastEthernet0/24成为新VLAN成员.但是网络管理员完成配置以后，主机A可以和主机B通信，但是主机A不能和主机C或者主机D通信。哪个命令可以用来解决这个问题？（）