单项选择题 On a Windows network, users are reporting that they cannot access any network resources. The users can ping the IP address and connect to the network resource using the IP address. Which of the following is the cause of the problem?（）

单项选择题 Which of the following does a star ring topology use for data transfer?（）

单项选择题 Which of the following network hardware allows the MOST network traffic collisions?（）