单项选择题 You are unable to telnet to a router at address 203.125.12.1 from a workstation with the IP address 203.125.12.23. You suspect that there is a problem with your protocol stack. Which of the following actions is most likely to confirm your diagnosis?（）

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?（）