Question No. 1

Which HDFS command uploads a local file X into an existing HDFS directory Y?

Ahadoop scp X Y

Bhadoop fs -localPut X Y

Chadoop fs-put X Y

Dhadoop fs -get X Y

Show Answer

Correct Answer: C

Question No. 2

Identify the MapReduce v2 (MRv2 / YARN) daemon responsible for launching application containers and monitoring application resource usage?

AResourceManager

BNodeManager

CApplicationMaster

DApplicationMasterService

ETaskTracker

FJobTracker

Show Answer

Correct Answer: B

Question No. 3

In a MapReduce job, the reducer receives all values associated with same key. Which statement best describes the ordering of these values?

AThe values are in sorted order.

BThe values are arbitrarily ordered, and the ordering may vary from run to run of the same MapReduce job.

CThe values are arbitrary ordered, but multiple runs of the same MapReduce job will always have the same ordering.

DSince the values come from mapper outputs, the reducers will receive contiguous sections of sorted values.

Show Answer

Correct Answer: B

Note:

* Input to theReduceris the sorted output of the mappers.

* The framework calls the application's Reduce function once for each unique key in the sorted order.

* Example:

For the given sample input the first map emits:

< Hello, 1>

< World, 1>

< Bye, 1>

< World, 1>

The second map emits:

< Hello, 1>

< Hadoop, 1>

< Goodbye, 1>

< Hadoop, 1>

Question No. 4

You have just executed a MapReduce job. Where is intermediate data written to after being emitted from the Mapper's map method?

AIntermediate data in streamed across the network from Mapper to the Reduce and is never written to disk.

BInto in-memory buffers on the TaskTracker node running the Mapper that spill over and are written into HDFS.

CInto in-memory buffers that spill over to the local file system of the TaskTracker node running the Mapper.

DInto in-memory buffers that spill over to the local file system (outside HDFS) of the TaskTracker node running the Reducer

EInto in-memory buffers on the TaskTracker node running the Reducer that spill over and are written into HDFS.

Show Answer

Correct Answer: C

The mapper output (intermediate data) is stored on the Local file system (NOT HDFS) of each individual mapper nodes. This is typically a temporary directory location which can be setup in config by the hadoop administrator. The intermediate data is cleaned up after the Hadoop Job completes.

Question No. 5

When can a reduce class also serve as a combiner without affecting the output of a MapReduce program?

AWhen the types of the reduce operation's input key and input value match the types of the reducer's output key and output value and when the reduce operation is both communicative and associative.

BWhen the signature of the reduce method matches the signature of the combine method.

CAlways. Code can be reused in Java since it is a polymorphic object-oriented programming language.

DAlways. The point of a combiner is to serve as a mini-reducer directly after the map phase to increase performance.

ENever. Combiners and reducers must be implemented separately because they serve different purposes.

Show Answer

Correct Answer: A

You can use your reducer code as a combiner if the operation performed is commutative and associative.

Free Hortonworks HDPCD Exam Actual Questions

The questions for HDPCD were last updated On Jan 13, 2025