单项选择题 An operator just completed a repair to a disk subsystem that contains a disk heartbeat. Before returning the system back into production mode， there is a requirement to verify the disk heartbeat is functioning.  How should the operator determine if the disk heartbeat network functioning？（）

单项选择题 WhatisaprerequisiteforusingtheapplicationavailabilityanalysistoolinHACMP？（）

单项选择题 A three-node cluster experienced a node failure. The resource groups were acquired as cexpected. The node has been repaired，and HACMP has been restarted.  How does the operator determine that the node has successfully re-integrated into the cluster？（）