单项选择题
Which of the following protocols would be used to test if one host is reachable by another host， by sending echo requests and waiting for echo replies？（）
A.SNMP B.ICMP C.TCP D.UDP
单项选择题 AsmallpushbuttontypicallyfoundontheinsideofaservercaseisMOSTlikelyusedforwhichof thefollowingpurposes？（）
单项选择题 Which of the following will allow devices to be added without turning the server off?（）
单项选择题 WhichofthefollowingisapublicIPaddress？（）
