Mapr (HP) Hadoop Developer Certification Questions and Answers (Dumps and Practice Questions)

Question : You have the following key-value pairs as output from your Map task:
(the, 1)
(fox, 1)
(faster, 1)
(than, 1)
(the, 1)
(dog, 1)
How many keys will be passed to the Reducer's reduce method?



1. Six
2. Five
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4. Two
5. One

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Explanation: Only one key value pair will be passed from the two (the, 1) key value pairs.




Question : You have a directory named jobdata in HDFS that contains four files: _first.txt, second.txt, .third.txt and #data.txt.
How many files will be processed by the FileInputFormat.setInputPaths () command when it's given a path object representing this
directory?


1. Four, all files will be processed
2. Three, the pound sign is an invalid character for HDFS file names
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4. None, the directory cannot be named jobdata
5. One, no special characters can prefix the name of an input file

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Explanation: Files starting with '_' are considered 'hidden' like unix files starting with '.'.
# characters are allowed in HDFS file names.




Question : On a cluster running MapReduce v (MRv), 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?

1. The amount of RAM installed on the TaskTracker node.
2. The amount of free disk space on the TaskTracker node.
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4. The average system load on the TaskTracker node over the past fifteen (15) minutes.
5. The location of the InsputSplit to be processed in relation to the location of the node.

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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.

Related Questions

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Question : Which statement is true about the storing files in HDFS



1. Files are split in the block
2. All the blocks of the files should remain on same machine
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4. All of the above
5. 1 and 3 are correct


Question : Select the correct statement ?

1. Block size is usually 64 MB or 128 MB
2. Blocks are replicated across multiple machine
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4. All of the above


Question : Which is the master node for tracking the files block in HDFS ?


1. JOBTracker
2. DataNode
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4. DataMasteNode


Question : Select the correct options


1. NameNode store the metadata for the files
2. DataNode holds the actual blocks
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4. All of the above
5. 1 and 2 are correct


Question : Select the correct statement for the NameNode ?


1. NameNode daemon must be running at all the times
2. NameNode holds all its metadata in RAM for fast access.
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4. 1,2 and 3 are correct
5. 1 and 2 are correct




Question : If NameNode stops, the cluster becomes inaccessible ?


1. True
2. Flase