Hortonworks Hortonworks Certifications APACHE-HADOOP-DEVELOPER Questions & Answers

• Question 51:

  You have user profile records in your OLPT database, that you want to join with web logs you have already ingested into the Hadoop file system. How will you obtain these user records?

  A. HDFS command

  B. Pig LOAD command

  C. Sqoop import

  D. Hive LOAD DATA command

  E. Ingest with Flume agents

  F. Ingest with Hadoop Streaming

  Correct Answer: C

  Reference: Hadoop and Pig for Large-Scale Web Log Analysis

• Question 52:

  On a cluster running MapReduce v1 (MRv1), a TaskTracker heartbeats into the JobTracker on your cluster, and alerts the JobTracker it has an open map task slot.

  What determines how the JobTracker assigns each map task to a TaskTracker?

  A. The amount of RAM installed on the TaskTracker node.

  B. The amount of free disk space on the TaskTracker node.

  C. The number and speed of CPU cores on the TaskTracker node.

  D. The average system load on the TaskTracker node over the past fifteen (15) minutes.

  E. The location of the InsputSplit to be processed in relation to the location of the node.

  Correct Answer: E

  Explanation: The TaskTrackers send out heartbeat messages to the JobTracker, usually every few minutes, to reassure the JobTracker that it is still alive. These message also inform the JobTracker of the number of available slots, so the JobTracker can stay up to date with where in the cluster work can be delegated. When the JobTracker tries to find somewhere to schedule a task within the MapReduce operations, it first looks for an empty slot on the same server that hosts the DataNode containing the data, and if not, it looks for an empty slot on a machine in the same rack.

  Reference: 24 Interview Questions and Answers for Hadoop MapReduce developers, How JobTracker schedules a task?

• Question 53:

  Which best describes how TextInputFormat processes input files and line breaks?

  A. Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the beginning of the broken line.

  B. Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReaders of both splits containing the broken line.

  C. The input file is split exactly at the line breaks, so each RecordReader will read a series of complete lines.

  D. Input file splits may cross line breaks. A line that crosses file splits is ignored.

  E. Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the end of the broken line.

  Correct Answer: A

  Reference: How Map and Reduce operations are actually carried out

• Question 54:

  Which YARN component is responsible for monitoring the success or failure of a Container?

  A. ResourceManager

  B. ApplicationMaster

  C. NodeManager

  D. JobTracker

  Correct Answer: A

• Question 55:

  Examine the following Hive statements:

  

  Assuming the statements above execute successfully, which one of the following statements is true?

  A. Each reducer generates a file sorted by age

  B. The SORT BY command causes only one reducer to be used

  C. The output of each reducer is only the age column

  D. The output is guaranteed to be a single file with all the data sorted by age

  Correct Answer: A

• Question 56:

  Given the following Pig commands: Which one of the following statements is true?

  

  A. The $1 variable represents the first column of data in 'my.log'

  B. The $1 variable represents the second column of data in 'my.log'

  C. The severe relation is not valid

  D. The grouped relation is not valid

  Correct Answer: B

• Question 57:

  Which one of the following Hive commands uses an HCatalog table named x?

  A. SELECT * FROM x;

  B. SELECT x.-FROM org.apache.hcatalog.hive.HCatLoader('x');

  C. SELECT * FROM org.apache.hcatalog.hive.HCatLoader('x');

  D. Hive commands cannot reference an HCatalog table

  Correct Answer: C

• Question 58:

  In a large MapReduce job with m mappers and n reducers, how many distinct copy operations will there be in the sort/shuffle phase?

  A. mXn (i.e., m multiplied by n)

  B. n

  C. m

  D. m+n (i.e., m plus n)

  E. mn (i.e., m to the power of n)

  Correct Answer: A

  Explanation: A MapReduce job with m mappers and r reducers involves up to m * r distinct copy operations, since each mapper may have intermediate output going to every reducer.

• Question 59:

  Which describes how a client reads a file from HDFS?

  A. The client queries the NameNode for the block location(s). The NameNode returns the block location(s) to the client. The client reads the data directory off the DataNode(s).

  B. The client queries all DataNodes in parallel. The DataNode that contains the requested data responds directly to the client. The client reads the data directly off the DataNode.

  C. The client contacts the NameNode for the block location(s). The NameNode then queries the DataNodes for block locations. The DataNodes respond to the NameNode, and the NameNode redirects the client to the DataNode that holds the requested data block(s). The client then reads the data directly off the DataNode.

  D. The client contacts the NameNode for the block location(s). The NameNode contacts the DataNode that holds the requested data block. Data is transferred from the DataNode to the NameNode, and then from the NameNode to the client.

  Correct Answer: A

  Reference: 24 Interview Questions and Answers for Hadoop MapReduce developers, How the Client communicates with HDFS?

• Question 60:

  Which one of the following files is required in every Oozie Workflow application?

  A. job.properties

  B. Config-default.xml

  C. Workflow.xml

  D. Oozie.xml

  Correct Answer: C