单项选择题
A.PIM-SM
B.PIM-DM
C.PIM-SSM
D.DVMRP
多项选择题 An802.1Qtrunkisnotcomingupbetweentwoswitches.Theportsonbothswitchesareconfiguredas"switchportmodedesirable."Assumingthatthereisnophysicalissue，choosetwopossiblecauses.（）
单项选择题 YoureplacedyourLayer3switch，whichisthedefaultgatewayoftheendusers.Manyuserscannotaccessanythingnow，includingemail，Internet，andotherapplications，althoughotherusersdonothaveanyissues.Alloftheapplicationsarehostedinanoutsourceddatacenter.Inordertofixtheproblem，whichoneoftheseactionsshouldyoutake？（）
多项选择题 WhichthreefieldsareoptionalinanOSPFv3externalLSA？（）