单项选择题
A.interface gig3/1 spanning-tree guard root
B.interface gig3/1 spanning-tree root guard
C.interface gig3/1 spanning-tree root-guard
D.interface gig3/1 spanning-tree root-guard default
单项选择题 WhichtypesofprefixeswillarouterrunningBGPmostlikelyadvertisetoanIBGPpeer，assumingitisnotconfiguredasaroutereflector？（）
多项选择题 Whichtwostatementsaretrueabout802.1s？（）
单项选择题 Totroubleshootnetworkissuesmoreaccurately，millisecondsshouldbeincludedinthesyslogoftherouter.Whichcommandwillachievethis？（）