单项选择题 A new server was installed. Most clients are located in the same subnet as the server and can successfully access the server. Clients located on different subnets have been unable to access the server， but have no trouble accessing other servers on their subnet.  Which of the following is the reason that these clients are unable to access the server？（）

单项选择题 A server is connected to a gigabit Ethernet switch and has negotiated 1Gbps / Full Duplex. When transferring large files to and from other servers on the segment via FTP slow performance is noticed.All network cabling，network hardware and server hardware were verified to be working correctly.  Which of the following could be done to improve performance？（）

单项选择题 A new server was installed for the purpose of monitoring network traffic. The network has been configured in such a way that all traffic will be mirrored out the port this server is connected to. When reviewing the network traffic logs on the server only traffic destined to the server is listed in the logs. Which of the following is preventing the server from seeing all network traffic？ （）