entStateLastChanged 1.3.6.1.2.1.131.1.1.1.1

The value of this object is the date and time when the value of any of entStateAdmin, entStateOper, entStateUsage, entStateAlarm, or entStateStandby changed for this entity. If there has been no change since the last re-initialization of the local system, this object contains the date and time of local system initialization. If there has been no change since the entity was added to the local system, this object contains the date and time of the insertion.