FREE Certified Data Professional (Big Data Hadoop Administrator) Questions and Answers

Question 1

When may the reduce method of a certain Reducer be invoked for the first time?

Accepted Answer

Not until all the Mappers have finished processing records

Answer

As soon as a Mapper has emitted at least one record

Answer

As soon as at least one Mapper has finished processing records

Answer

It depends on the InputFormat used for the job

Question 2

How can a client access a file on HDFS?

Accepted Answer

For the block location, the client contacts the NameNode (s). The NameNode then requests block locations from the DataNodes. The NameNode leads the client to the DataNode, holding the requested data block when the DataNodes react to it (s). Data is then read directly from the DataNode by the client.

Answer

The client asks NameNode where the block is located (s). The NameNode gives the client the block location(s) back. Data is immediately read by the client from the DataNode (s)

Answer

The client simultaneously requests every DataNode. The client receives a response from the DataNode with the requested data. Data is immediately read by the client from the DataNode.

Answer

For the block location, the Client contacts the NameNode (s). The NameNode contacts the DataNode that contains the desired data block. Data is exchanged from the DataNode to the NameNode to the Client from the NameNode to the Client.

Question 3

You are creating a combiner that receives input in text keys and IntWritable values and outputs text keys and IntWritable values. Which interface ought to be implemented by your class?

Accepted Answer

Answer

Reducer <Text, IntWritable, Text, IntWritable>

Answer

Combiner <Text, IntWritable, Text, IntWritable>

Answer

Reducer <Text, Text, IntWritable, IntWritable>

Answer

Combiner <Text, Text, IntWritable, IntWritable>

Question 4

Which tool enables you to use any executable script as the Mapper or Reducer to generate and run MapReduce jobs?

Accepted Answer

Hadoop Streaming

Answer

Oozie

Answer

Flume

Answer

Sqoop

Question 5

During a typical sort and shuffle phase of MapReduce, how are keys and data presented and delivered to Reducers?

Accepted Answer

Keys are presented to a Reducer in sorted order; values for a given key are not sorted

Answer

Keys are presented to a Reducer in sorted order; values for a given key are sorted in ascending orde

Answer

Keys are presented to a Reducer in random order; values for a given key are sorted in ascending order

Answer

Keys are presented to a Reducer in random order; values for a given key are not sorted

Question 6

Which best reflects the sequence in which data is supplied to a Reducer's reduce function, assuming default settings?

Accepted Answer

The keys given to a Reducer are in sorted order, but the values associated with each key are in no predictable order

Answer

Neither keys nor values are in any predictable order

Answer

The keys given to a Reducer aren't in a predictable order, but the values associated with those keys always are

Answer

Both the keys and values passed to a Reducer always appear in sorted order

Question 7

Which Linux command enables the display of a file or directory indication?

Accepted Answer

ls -l.

Answer

man ls.

Answer

ls.

Answer

ls -a.