Given the following cluster.mmddyyyy log file output, what has happened?
Mar 29 06:09:22 EVENT START: network_down -1 net_ether_01
Mar 29 06:09:22 EVENT COMPLETED: network_down -1 net_ether_01 0
Mar 29 06:09:29 EVENT START: network_down_complete -1 net_ether_01
Mar 29 06:09:29 EVENT COMPLETED: network_down_complete -1 net_ether_01 0

A.
Non-redundant network switch has failed

B.
One interface in net_ether_01 has failed

C.
The service IP address was moved to another adapter

D.
Some heartbeat packets have been lost on one node in a cluster