单项选择题 Which of the following protocols uses port 119, by default?（）

单项选择题 When the DHCP server is unavailable for a network, how will PCs attempt to configure their NICs?（）

单项选择题 A user is trying to connect their new desktop to the network but is unable to get an IP address. The technician tests the cable and finds that there are too many open pairs. Which of the following wiring standards needs to be used in the replacement cable?（）