Free Cloudera Certified Administrator for Apache Hadoop (CCAH) Practice Questions

A.  

Run hdfs fs –du / and locate the DFS Remaining value

B.  

Run hdfs dfsadmin –report and locate the DFS Remaining value

C.  

Run hdfs dfs / and subtract NDFS Used from configured Capacity

D.  

Connect to http://mynamenode:50070/dfshealth.jsp and locate the DFS remaining value

A.  

Without creating a dfs.hosts file or making any entries, run the commands hadoop.dfsadmin-refreshModes on the NameNode

B.  

Restart the NameNode

C.  

Creating a dfs.hosts file on the NameNode, add the worker Node’s name to it, then issue the command hadoop dfsadmin –refresh Nodes = on the Namenode

D.  

Nothing; the worker node will automatically join the cluster when NameNode daemon is started

A.  

User authentication on all remote procedure calls (RPCs)

B.  

Encryption for data during transfer between the Mappers and Reducers

C.  

Encryption for data on disk (“at rest”)

D.  

Authentication for user access to the cluster against a central server

E.  

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

A.  

Yes. The daemon will receive data from the NameNode to run Map tasks

B.  

Yes. The daemon will get data from another (non-local) DataNode to run Map tasks

C.  

Yes. The daemon will receive Map tasks only

D.  

Yes. The daemon will receive Reducer tasks only

A.  

Modify yarn-site.xml with the following property:

yarn.scheduler.minimum-allocation-mb

2048

B.  

Modify yarn-sites.xml with the following property:

yarn.scheduler.minimum-allocation-mb

4096

C.  

Modify yarn-site.xml with the following property:

yarn.nodemanager.resource.cpu-vccores

D.  

No action is needed: YARN’s dynamic resource allocation automatically optimizes the node memory and cores

A.  

The file will remain under-replicated until the administrator brings that node back online

B.  

The cluster will re-replicate the file the next time the system administrator reboots the NameNode daemon (as long as the file’s replication factor doesn’t fall below)

C.  

This will be immediately re-replicated and all other HDFS operations on the cluster will halt until the cluster’s replication values are resorted

D.  

The file will be re-replicated automatically after the NameNode determines it is under-replicated based on the block reports it receives from the NameNodes

A.  

The NameNode will update the dfs.hosts property to include machines running the DataNode daemon on the next NameNode reboot or with the command dfsadmin –refreshNodes

B.  

No new nodes can be added to the cluster until you specify them in the dfs.hosts file

C.  

Any machine running the DataNode daemon can immediately join the cluster

D.  

Presented with a blank dfs.hosts property, the NameNode will permit DataNodes specified in mapred.hosts to join the cluster

A.  

When Job B gets submitted, it will get assigned tasks, while job A continues to run with fewer tasks.

B.  

When Job B gets submitted, Job A has to finish first, before job B can gets scheduled.

C.  

When Job A gets submitted, it doesn’t consumes all the task slots.

D.  

When Job A gets submitted, it consumes all the task slots.

A.  

The DataNode JVM on one host is not active

B.  

Because your under-replicated blocks count matches the Live Nodes, one node is dead, and your DFS Used % equals 0%, you can’t be certain that your cluster has all the data you’ve written it.

C.  

Your cluster has lost all HDFS data which had bocks stored on the dead DatNode

D.  

The HDFS cluster is in safe mode