多项选择题
Which three of the following OSI model layers also belong to the TCP/IP model?（）
A. The application layer B. The session layer C. The data link layer D. The transport layer E. The network interface layer F. The physical layer
单项选择题 Which one of the following is the most commonly used layer 2 network device?（）
多项选择题 In the OSI model, at which layers do WANs operate at?（）
单项选择题 At which layer of the OSI model is the optimal path to a network destination determined at?（）
