单项选择题
A. ping 127.0.0.0
B. ping 203.125.12.1
C. telnet 127.0.0.1
D. ping 127.0.0.1
E. tracert 203.125.12.1
单项选择题 Why would an administrator change the value of the spanning-tree priority of a switch?（）
多项选择题 Which of the following components must be elected before the Spanning Tree Protocol can converge in a switched LAN?（）
单项选择题 What is the subnetwork number of a host with an IP address of 172.16.210.0/22?（）