单项选择题
A.data link layer
B.application layer
C.access layer
D.session layer
E.network layer
多项选择题 Refer to the exhibit. The two connected ports on the switch are not turning orange or green. What would be the most effective steps to troubleshoot this physical layer problem?（）
单项选择题 Which port state is introduced by Rapid-PVST?（）
单项选择题 Refer to the exhibit.HostA cannot ping HostB.Assuming routing is properly configured,what could be the cause of this problem?（）
