CDP (Big Data Hadoop Administrator) 4

Question 1

Which Hadoop HA component acts as a shared storage for edit logs between the Active and Standby NameNodes?

Accepted Answer

Journal Nodes

Answer

In HDFS HA, Journal Nodes form a quorum that both the Active and Standby NameNodes write to and read from for edit log synchronization.

Question 2

A cluster administrator needs to decommission a DataNode gracefully. What is the correct sequence of actions?

Accepted Answer

Add the DataNode to dfs.hosts.exclude, refresh the NameNode, wait for decommission to complete

Answer

Graceful decommission requires adding the node to the exclude list, running refreshNodes, and waiting for HDFS to replicate all blocks elsewhere before stopping the node.

Question 3

What does the 'mapreduce.job.reduces' parameter control?

Accepted Answer

The number of reduce tasks for a MapReduce job

Answer

mapreduce.job.reduces specifies how many reducer tasks the framework will spawn for a given MapReduce job.

Question 4

Which Hadoop tool is used to balance block distribution across DataNodes?

Accepted Answer

hdfs balancer

Answer

The hdfs balancer command redistributes HDFS blocks across DataNodes to equalize disk utilization.

Question 5

In YARN's Fair Scheduler, what is 'preemption' and when does it occur?

Accepted Answer

Terminating containers from over-served queues to free resources for under-served queues

Answer

Preemption allows the Fair Scheduler to reclaim resources from queues exceeding their fair share and give them to queues that are below their share.

CDP - Certified Data Professional Practice Test

CDP - Certified Data Professional Practice Test

CDP (Big Data Hadoop Administrator) 4