routingincircuit-switchingnetworkshastraditionallyinvolvedastaticroutingstrategywiththeuseof(71)pathstorespondtoincreasedload.modernroutingstrategiesprovidemoreadaptiveandflexibleapproaches.theroutingfunctionofapacket-switchingnetworkattemptstofindtheleast-costroutethroughthenetwork,withcostbasedonthenumberofexpecteddelay,orothermetricsinvirtuallyallpacket-switchingnetworks,somesortfadaptiveroutingtechniqueisused.adaptiveroutingalgorithmstypicallyrelyonthe(73)informationabouttrafficconditionsamongnodes.inmostcases,adaptivestrategiesdependnstatusinformationthatis(74)atoneplacebutusedatanother.thereisatradeoffheretweenthequalityoftheinformationandtheamountof(75).theexchangedinformationitselfaloadontheconstituentnetworks,causingaperformancedegradation
A.only
B.single
C.alternate
D.series
正确答案是C