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?（）
A.The file server is offline. B.The DNS server is not resolving correctly. C.The DHCP server is not assigning correct IP addresses. D.The domain controller is not responding.
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?（）
单项选择题 In the OSI model, which of the following layers would be the cause of a session time-out while browsing the web?（）
