Hadoop Multiple Choice Questions And Answers

21. The size of block in HDFS is
A. 512 bytes
B. 64 MB
C. 1024 KB
D. None of the above
Answer: B

22. The switch given to “hadoop fs” command for detailed help is
A. -show
B. -help
C. -?
D. None of the above
Answer: B

23. RPC means
A. Remote processing call
B. Remote process call
C. Remote procedure call
D. None of the above
Answer: C

24. Which method of the FileSystem object is used for reading a file in HDFS
A. open()
B. access()
C. select()
D. None of the above
Answer: A

25. How many states does Writable interface defines
A. Two
B. Four
C. Three
D. None of the above
Answer: A

26. What are supported programming languages for Map Reduce?
A. The most common programming language is Java, but scripting languages are also supported via Hadoop streaming.
B. Any programming language that can comply with Map Reduce concept can be supported.
C. Only Java supported since Hadoop was written in Java.
D. Currently Map Reduce supports Java, C, C++ and COBOL.
Answer: A

28. What are sequence files and why are they important?
A. Sequence files are binary format files that are compressed and are splitable. They are often used in high-performance map-reduce jobs
B. Sequence files are a type of the file in the Hadoop framework that allow data to be sorted
C. Sequence files are intermediate files that are created by Hadoop after the map step
D. Both B and C are correct
Answer: A

29. What are map files and why are they important?
A. Map files are stored on the namenode and capture the metadata for all blocks on a particular rack.
This is how Hadoop is "rack aware"
B. Map files are the files that show how the data is distributed in the Hadoop cluster.
C. Map files are generated by Map-Reduce after the reduce step. They show the task distribution during job execution
D. Map files are sorted sequence files that also have an index. The index allows fast data look up.
Answer: D

30. How can you use binary data in MapReduce?
A. Binary data can be used directly by a map-reduce job. Often binary data is added to a sequence file.
B. Binary data cannot be used by Hadoop fremework. Binary data should be converted to a Hadoop compatible format prior to loading.
C. Binary can be used in map-reduce only with very limited functionlity. It cannot be used as a key for example.
D. Hadoop can freely use binary files with map-reduce jobs so long as the files have headers
Answer: A

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