ThediffservapproachtoprovidingQoSinnetworksemploysasmall,well-definedsetofbuildingblocksfromwhichyoucanbuildavarietyof().Itsaimistodefinethedifferentiatedservices(DS)byte,theTypeofService(ToS)bytefromtheInternetProtocolVersion4()andtheTrafficClassbytefromIPVersion6,andmarkthestandardizedDSbyteofthepacketsuchthatitreceivesaparticularforwardingtreatment,orper-hopbehavior(PH B),ateachnetworknode.Thediffservarchitectureprovidesa()withinwhichserviceproviderscanoffercustomersarangeofnetworkservices,eachdifferentiatedbasedonperformance.Acustomercanchoosethe(________)levelneededonapacket-by-packetbasisbysimplymarkingthepacket'sDifferentiatedServicesCodePoint(DSCP)fieldtoaspecificvalue.This()specifiesthePHBgiventothepacketwithintheserviceprovidernetwork。横线处应选()
A.performance
B.Secure
C.privacy
D.data
正确答案是A