Assuming a large properly configured multi-rack Hadoop cluster, which scenario should not result
in loss of HDFS data assuming the default replication factor settings?

A.
Ten percent of DataNodes simultaneously fail.

B.
All DataNodes simultaneously fail.

C.
An entire rack fails.

D.
Multiple racks simultaneously fail.

E.
Seventy percent of DataNodes simultaneously fail.

Explanation:
http://stackoverflow.com/questions/12399197/in-a-large-properly-configured-multirack-hadoop-cluster-which-scenarios-will-b