多项选择题
A.root guard
B.loop guard
C.BPDU guard
D.UDLD
E.BPDU skew detection
单项选择题 Whileyouaretroubleshootingnetworkperformanceissues，younoticethataswitchisperiodicallyfloodingallunicasttraffic.FurtherinvestigationrevealsthatperiodicallytheswitchisalsohavingspikesinCPUutilization，causingtheMACaddresstabletobeflushedandrelearned.Whatisthemostlikelycauseofthisissue？（）
单项选择题 ForarouterconnectedtotwoISPsforredundancy，usingIPSLAandstaticrouting，howwouldyouconfigureuRPFontheuplinkinterface？（）
多项选择题 Voicequalityisbadduetohighdelayandjitteronalink.Whichtwoactionswillimprovethequalityofvoicecalls？（）