单项选择题
A. Yellow question mark next to device
B. Black checkmark next to device
C. Yellow exclamation point next to device
D. Red X next to the device
单项选择题 A client is having trouble connecting to the Internet. The client is using a static IP address and is able to connect to other devices on the network via IP address only. Which of the following is MOST likely the problem?（）
单项选择题 A computer that has dynamic IP addressing is not receiving an IP address. Which of the following is MOST likely the problem?（）
单项选择题 Which of the following should be used to check a serial port for functionality?（）