Hadoop Interview Questions and Answers

This set of Hadoop Interview Questions & Answers focuses on “MapReduce Development – 1”.

1. ________ job usually splits the input data-set into independent chunks which are processed by the map tasks in a completely parallel manner.
a) Tasker
b) MapReduce
c) Tasktrack
d) None of the mentioned
View Answer

Answer: b
Explanation: Hadoop MapReduce is a software framework for easily writing applications that process vast amounts of data.

2. Point out the correct statement.
a) Another limitation of the Hadoop MapReduce framework is its pull-based scheduling model
b) The MapReduce framework sorts the outputs of the maps, which are then input to the reduce tasks
c) The MapReduce framework takes care of scheduling tasks, monitoring them and re-executes the failed tasks
d) All of the mentioned
View Answer

Answer: d
Explanation: Typically both the input and the output of the job are stored in a file-system.

3. Hadoop __________ is a utility which allows users to create and run jobs with any executables.
a) Streaming
b) Pipes
c) Orchestration
d) All of the mentioned
View Answer

Answer: a
Explanation: Applications specify the input/output locations and supply map and reduce functions.

4. Hadoop _________ is a SWIG- compatible C++ API to implement MapReduce applications.
a) Streaming
b) Pipes
c) Orchestration
d) All of the mentioned
View Answer

Answer: b
Explanation: The MapReduce framework operates exclusively on pairs.

5. Point out the wrong statement.
a) MapReduce configuration allows the framework to effectively schedule tasks on the nodes where data is already present
b) Typically the compute nodes and the storage nodes are different
c) The MapReduce framework consists of a single master JobTracker and one slave TaskTracker per cluster-node
d) None of the mentioned
View Answer

Answer: b
Explanation: MapReduce framework and the Hadoop Distributed File System are running on the same set of nodes.

6. The key and value classes have to be _________ by the Mapreduce framework.
a) collected
b) serializable
c) compacted
d) none of the mentioned
View Answer

Answer: b
Explanation: Writable interface needs to be implemented for key classes.

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7. Key classes have to implement the __________ interface to facilitate sorting by the framework.
a) Writable
b) Comparable
c) WritableComparable
d) None of the mentioned
View Answer

Answer: c
Explanation: Input and Output types of a MapReduce job:(input) <k1, v1> -> map -> <k2, v2> -> combine -> <k2, v2> -> reduce -> <k3, v3> (output).

8. The ________ option allows applications to add jars to the classpaths of the maps and reduces.
a) optionname
b) -libjars
c) -archives
d) all of the mentioned
View Answer

Answer: b
Explanation: Applications can specify a comma separated list of paths which would be present in the current working directory of the task using the option -files.

9. The option ___________ allows to pass comma separated list of archives as arguments.
a) optionname
b) -libjars
c) -archives
d) none of the mentioned
View Answer

Answer: c
Explanation: These archives are unarchived and a link with name of the archive is created in the current working directory of tasks.

10. Users can specify a different symbolic name for files and archives passed through -files and -archives option, using __________
a) $
b) @
c) #
d) $
View Answer

Answer: c
Explanation: MapReduce is the primary method for non-primary-key-based querying.

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