单项选择题
A. Enables all fiber-optic LAN ports for Unidirectional LINK Detection （UDLD）
B. Enables all copper media LAN ports Unidirectional Link Detection （UDLD）
C. Overrides the default UDLS setting for all ports
D. Globally enables all ports on the device for Unidirectional Link Detection （UDLS）
E. None of the other alternatives apply
单项选择题 Switch R1 has been configured with the root guard feature. What statement is true if the spanning tree enhancement Root Guard is enabled？ （）
多项选择题 You are the network administrator tasked with designing a switching solution for the Company network. Which of the following statements describing trunk links are INCORRECT？（）
多项选择题 ISL is being configured on a Company switch. Which of the following choices are true regarding the ISL protocol？ （）