1. [单选题]把指定端口添加到VLAN的命令是：()
A. vlan
B. vlan-member ship
C. vtp
D. switch port
2. [单选题]What is the purpose of the Spanning Tree Protocol (STP)?
A. To prevent routing loops
B. To create a default route
C. To provide multiple gateways for hosts
D. To maintain a loop-free Layer 2 network topology
E. To enhance the functions of SNMP
3. [单选题]路由器上“水平分割”的功能是：()
A. 分离端口
B. 阻止路由环路
C. 简化配置
D. 方便故障处理
