1. [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
2. [单选题]在启用IGRP协议时，所需要的参数是：()
A. 网络掩码
B. 子网号
C. 自治系统号
D. 跳数
3. [单选题]介质100BaseT的最大传输距离是：()
A. 10m
B. 100m
C. 1000m
D. 500m
