WhichthreestatementsaboutSTPtimersaretrue?()

A.STPtimersvalues（hello，forwarddelay，maxage）areincludedineachBPDU.

B.AswitchisnotconcernedaboutitslocalconfigurationoftheSTPtimersvalues.ItwillonlyconsiderthevalueoftheSTPtimerscontainedintheBPDUitisreceiving.

C.TosuccessfullyexchangeBPDUsbetweentwoswitches，theirSTPtimersvalue（hello，forwarddelay，maxage）mustbethesame.

D.IfanySTPtimervalue（hello，forwarddelay，maxage）needstobechanged，itshouldatleastbechangedontherootbridgeandbackuprootbridge.

E.Onaswitchednetworkwithasmallnetworkdiameter，theSTPhellotimercanbetunedtoalowervaluetodecreasetheloadontheswitchCPU.

F.TherootbridgepassesthetimerinformationinBPDUstoallroutersintheLayer3configuration.