Which two features does Kerberos security add to a Hadoop cluster?

A.
Authentication for user access to the cluster against a central server

B.
Encryption for data on disk (“at rest”)

C.
Encryption on all remote procedure calls (RPCs)

D.
User authentication on all remote procedure calls (RPcs)

E.
Root access to the cluster for users hdfs and mapred but non-root acess clients

Explanation:
Hadoop can use the Kerberos protocol to ensure that when someone makes a request, they really
are who they say they are. This mechanism is used throughout the cluster. In a secure Hadoop
configuration, all of the Hadoop daemons use Kerberos to perform mutual authentication, which
means that when two daemons talk to each other, they each make sure that the other daemon is
who it says it is. Additionally, this allows the NameNode and JobTracker to ensure that any HDFS
or MR requests are being executed with the appropriate authorization level.
Documentation CDH3 Documentation CDH3 Security Guide, Introduction to Hadoop

Security