简答题 four switches， which one will be root switch.（no pic）.

问答题hsrpspeak状态是什么意思？

问答题port-security的restrictaction是什么意思？

问答题spanning-tree关于listeningandlearningtime如何adjustandchangeamountoftime？

问答题WhichOSPFnetworktypeisidealforpartiallymeshedNBMAnetworksbecauseitiseasytoconfigure（requiresnoconfigurationofneighborcommands），consumesonlyoneIPsubnet，andrequiresnodesignatedrouterelection？

问答题WhichOSPFfeatureallowsaroutertocontinuetoforwardpacketswhileundergoingspecific，well-knownfailureconditions？