单项选择题
A.Upgrade the switches
B.Configure BPDU guard
C.Configure VLAN access lists
D.Configure port security
E.Configure Dynamic ARP inspection
单项选择题 Whentroubleshootingtheissue，younoticetheelectionofanewrootbridgewithanunknownMACaddress.KnowingthatallaccessportshavethePortFastfeatureenabled，whatwouldbetheeasiestwaytoresolvetheissuewithoutlosingredundantlinks？（）
多项选择题 Youarethenetworkadministratorofamedium-sizedcompany，andusersarecomplainingthattheycannotsendemailstosomeorganizations.Duringyourtroubleshooting，younoticethatyourDNSMXrecordisblacklistedbyseveralpublicblacklistfilters.AfterclearingtheselistingsforyourIPaddress，andassumingthatyouremailserverhastherightvirusprotectioninplace，whataretwopossiblesolutionstopreventthisfromhappeninginthefuture？（）
单项选择题 AfterapplyinganewACLonadevice，itsCPUutilizationrosesignificantlyandmanymessagesstartingwith"%SEC-6-IPACCESSLOG"appearedontheSyslogserver.Whatcanbedonetoresolvethissituation？（）