单项选择题
Ensuring that data is transmitted securely over an IP network is the main purpose of：（）
A.Telnet B.FTP C.SIP D.TLS
单项选择题 WhichofthefollowingisSTPBESTidentifiedbyunderthecablesheath？（）
多项选择题 Whichofthefollowingwouldbeconsideredaroutingprotocol？（）
单项选择题 WhichofthefollowingnetworkservicesisresponsibleformappingnamestoIPaddresses？（）
