多项选择题
A network administrator issues the ping 192.168.2.5 command and successfully tests connectivity to a host that has been newly connected to the network. Which protocols were used during the test?（）
A. ARP B. CDP C. DHCP D. DNS E. ICMP
单项选择题 What is the purpose of Spanning Tree Protocol?（）
单项选择题 What is the function of the CSMA/CD algorithm in Ethernet technologies?（）
单项选择题 What value is primarily used to determine which port becomes the root port on each non root switch in a spanning-tree topology?（）
