VTL 6900 Engines a and B Nodes Form a Cluster

VTL 6900 engines A and B nodes form a cluster, on the A, B node between the business bearer and the fault automatically switch, which of the following description is correct? (Multiple choice)

A) When the node a is found through the sms -v command, the status of the IPStor Authentication Module is FAIL. The service of the node A will be from Move to Node B
B) unplug the A node power supply, A node's business will automatically switch to the B node
C) unplug the A node and the backup server network connection, the A node's business will automatically switch to the B node
D) A, B nodes can work in Active-Active mode, but can only manually achieve the backup service load balancing between A and B nodes