单项选择题 Which of the following are considered link state protocols?（）

单项选择题 According to the OSI model, which of the following layers is responsible for providing reliablecommunication?（）

单项选择题 A technician receives a call on monday morning that several computers will not connect to the network. The technician determines that the computers left on over the weekend are functional and those that were turned off over the weekend are not functioning. Which of the following is the MOST likely source of the problem?（）