A.Upgrade the switchesB.Configure BPDU guardC.Configure……

单项选择题Whentroubleshootingtheissue，younoticetheelectionofanewrootbridgewithanunknownMACaddress.KnowingthatallaccessportshavethePortFastfeatureenabled，whatwouldbetheeasiestwaytoresolvetheissuewithoutlosingredundantlinks？（）

A.Enable bpduguard globally.
B.Enable rootguard.
C.Enable loopguard.
D.Enable spanning tree.
E.Enable UDLD

多项选择题Youarethenetworkadministratorofamedium-sizedcompany，andusersarecomplainingthattheycannotsendemailstosomeorganizations.Duringyourtroubleshooting，younoticethatyourDNSMXrecordisblacklistedbyseveralpublicblacklistfilters.AfterclearingtheselistingsforyourIPaddress，andassumingthatyouremailserverhastherightvirusprotectioninplace，whataretwopossiblesolutionstopreventthisfromhappeninginthefuture？（）

A.Change your Internet provider.
B.Change your public IP address.
C.Allow the email server to send traffic only to TCP port 25.
D.Put your email server in a DMZ.
E.Use a separate public IP address for your email server only.

单项选择题AfterapplyinganewACLonadevice，itsCPUutilizationrosesignificantlyandmanymessagesstartingwith %SEC-6-IPACCESSLOG appearedontheSyslogserver.Whatcanbedonetoresolvethissituation？（）

A.Increase memory allocation for ACLs.
B.Remove all entries from the ACL and use a single permit ip any any statement.
C.Remove the log keyword from each ACL entry.
D.Reboot the device after the ACL has been applied.

单项选择题WhichfeaturewouldpreventguestusersfromgainingnetworkaccessbyunplugginganIPphoneandconnectingalaptopcomputer？（）

A.IPSec VPN
B.SSL VPN
C.port security
D.port security with statically configured MAC addresses
E.private VLANs

多项选择题Yournetworkissufferingfromregularoutages.Aftertroubleshooting，youlearnthatthetransmitleadofafiberuplinkwasdamaged.Whichtwofeaturescanpreventthesameissuesinthefuture？（）

A.root guard
B.loop guard
C.BPDU guard
D.UDLD
E.BPDU skew detection