单项选择题 An administrator is troubleshooting a communication issue between two computers on the same Layer 2 switch. Which of the following is the BEST way to determine if the switch is causing the issue?（）

单项选择题 Which of the following is equipment provided by the telephone company that provides remotediagnostic and loopback services for subscriber lines?（）

单项选择题 Which of the following routing protocols runs over UDP and determines path based upon distancevectors?（）