MCQ Collection
Big Data Analytics MCQs
Practice Big Data Analytics questions with answers and explanations.
Choose an option to check your answer.
A.
A fixed-size chunk into which a file is divided
B.
A complete database row
C.
A YARN container
D.
A Scala object
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Correct Answer: A. A fixed-size chunk into which a file is divided
Explanation:
Files are split into blocks that can be stored on different DataNodes.
Choose an option to check your answer.
A.
Obtaining block locations from the NameNode and reading data directly from DataNodes
B.
Reading all bytes through the NameNode
C.
Allocating YARN containers
D.
Compiling the mapper code
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Correct Answer: A. Obtaining block locations from the NameNode and reading data directly from DataNodes
Explanation:
The NameNode supplies metadata rather than streaming user data.
Choose an option to check your answer.
A.
The framework does not guarantee that a combiner will run
B.
The combiner always runs after the reducer
C.
Combiners cannot emit keys
D.
Combiners operate on final output only
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Correct Answer: A. The framework does not guarantee that a combiner will run
Explanation:
A combiner is an optimization rather than a required semantic stage.
Choose an option to check your answer.
A.
Adding an extra value to a hot key to spread its records across partitions
B.
Encrypting keys for security
C.
Sorting keys by length
D.
Removing repeated keys
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Correct Answer: A. Adding an extra value to a hot key to spread its records across partitions
Explanation:
Salting creates multiple temporary versions of a frequent key.
Choose an option to check your answer.
A.
A key made from multiple fields
B.
A key shared by all records
C.
An encrypted HDFS path
D.
A reducer identifier
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Correct Answer: A. A key made from multiple fields
Explanation:
Composite keys support partitioning, grouping, and secondary sort logic.
Choose an option to check your answer.
A.
Splitting a record into columns
B.
Storing multiple copies of data on different nodes
C.
Sorting all data globally
D.
Replacing raw data with summaries
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Correct Answer: B. Storing multiple copies of data on different nodes
Explanation:
Replication improves availability and fault tolerance.
Choose an option to check your answer.
A.
The number of blocks in a file
B.
The number of copies maintained for each block
C.
The number of NameNodes
D.
The number of users accessing a file
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Correct Answer: B. The number of copies maintained for each block
Explanation:
Replication protects data from disk and node failures.
Choose an option to check your answer.
A.
A SQL execution plan
B.
A chain of DataNodes through which a block and its replicas are written
C.
A list of NameNode commands only
D.
A Scala collection transformation
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Correct Answer: B. A chain of DataNodes through which a block and its replicas are written
Explanation:
The client sends packets to the first DataNode, which forwards them along the pipeline.
Choose an option to check your answer.
A.
Computing an unweighted average from partial averages
B.
Summing counts for the same key
C.
Selecting a globally ordered median
D.
Assigning unique sequence numbers
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Correct Answer: B. Summing counts for the same key
Explanation:
Addition is associative and commutative, so partial sums can be merged safely.
Choose an option to check your answer.
A.
Executing every job twice from the start
B.
Running duplicate attempts of unusually slow tasks
C.
Running reducers before mappers finish
D.
Copying HDFS data to every node
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Correct Answer: B. Running duplicate attempts of unusually slow tasks
Explanation:
The framework may launch another attempt on a different node.
Choose an option to check your answer.
A.
To compare job durations
B.
To define which sorted intermediate keys are treated as one reducer group
C.
To choose the number of mappers
D.
To verify HDFS checksums
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Correct Answer: B. To define which sorted intermediate keys are treated as one reducer group
Explanation:
Grouping can ignore part of a composite key while sort order uses all fields.
Choose an option to check your answer.
A.
Defining a rigid schema before storing any data
B.
Rejecting semi-structured data
C.
Applying structure when data is queried or analyzed
D.
Encrypting data before use
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Correct Answer: C. Applying structure when data is queried or analyzed
Explanation:
Schema-on-read keeps raw data flexible until analysis time.
