单项选择题 TCP/IP refers to a suite of ( ).unitsC、application programsD、data communication protocols

单项选择题 The Address Resolution Protocol(ARP) is employed at ( ).Interface LayerB、Internetwork LayerC、Host-to-Host Transport LayerD、Application Layer

单项选择题 Virtual Private Networks(VPN) are networks deployed on a ( ) network infrastructure.areaD、wide area