单项选择题 A technician is troubleshooting a network connectivity issue. Given the following abbreviated trace route output: Which of the following is MOST likely occurring?（）

单项选择题 At which of the following layers does the TCP protocol operate?（）

单项选择题 A user on a network cannot access any network resources. The link light on the computer showsthat a connection is present. Which of the following is the MOST likely cause of the problem?（）