单项选择题
A computer is connected to the network through a NIC， which has a unique assignment that is called the Ethernet MAC address. Which layer of the OSI model does the MAC address use to communicate with the network？（）
A. network B. application C. session D. data link
多项选择题 AddresstranslationisanothercomponentofLayer3design.WhichtwotypesofaddresstranslationallowanIPAddresstobeduplicated？（）
多项选择题 WhichtwoWANinterfacesdoestheCiscoSRP520Seriessupport？（）
多项选择题 WhatarethreefeaturesthatareincludedwiththepurchaseofaCiscoSA520？（）
