Hadoop MapReduce MCQs
Hadoop MapReduce MCQs : This section focuses on "MapReduce" in Hadoop. These Multiple Choice Questions (MCQ) should be practiced to improve the hadoop skills required for various interviews (campus interviews, walk-in interviews, company interviews), placements, entrance exams and other competitive examinations.
1. The MapReduce algorithm contains two important tasks, namely __________.
A. mapped, reduce
B. mapping, Reduction
C. Map, Reduction
D. Map, Reduce
View Answer
Ans : D
Explanation: The MapReduce algorithm contains two important tasks, namely Map and Reduce.
2. _____ takes a set of data and converts it into another set of data, where individual elements are broken down into tuples (key/value pairs).
A. Map
B. Reduce
C. Both A and B
D. Node
View Answer
Ans : A
Explanation: Map takes a set of data and converts it into another set of data, where individual elements are broken down into tuples (key/value pairs).
3. ______ task, which takes the output from a map as an input and combines those data tuples into a smaller set of tuples.
A. Map
B. Reduce
C. Node
D. Both A and B
View Answer
Ans : B
Explanation: Reduce task, which takes the output from a map as an input and combines those data tuples into a smaller set of tuples.
4. In how many stages the MapReduce program executes?
A. 2
B. 3
C. 4
D. 5
View Answer
Ans : B
Explanation: MapReduce program executes in three stages, namely map stage, shuffle stage, and reduce stage.
5. Which of the following is used to schedules jobs and tracks the assign jobs to Task tracker?
A. SlaveNode
B. MasterNode
C. JobTracker
D. Task Tracker
View Answer
Ans : C
Explanation: JobTracker : Schedules jobs and tracks the assign jobs to Task tracker.
6. Which of the following is used for an execution of a Mapper or a Reducer on a slice of data?
A. Task
B. Job
C. Mapper
D. PayLoad
View Answer
Ans : A
Explanation: Task : An execution of a Mapper or a Reducer on a slice of data.
7. Which of the following commnd runs a DFS admin client?
A. secondaryadminnode
B. nameadmin
C. dfsadmin
D. adminsck
View Answer
Ans : C
Explanation: dfsadmin : Runs a DFS admin client.
8. Point out the correct statement.
A. MapReduce tries to place the data and the compute as close as possible
B. Map Task in MapReduce is performed using the Mapper() function
C. Reduce Task in MapReduce is performed using the Map() function
D. None of the above
View Answer
Ans : A
Explanation: This feature of MapReduce is "Data Locality".
9. Although the Hadoop framework is implemented in Java, MapReduce applications need not be written in ____________
A. C
B. C#
C. Java
D. None of the above
View Answer
Ans : C
Explanation: Hadoop Pipes is a SWIG- compatible C++ API to implement MapReduce applications (non JNITM based).
10. The number of maps is usually driven by the total size of ____________
A. Inputs
B. Output
C. Task
D. None of the above
View Answer
Ans : A
Explanation: Total size of inputs means the total number of blocks of the input files.
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