MCQs

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Overall MCQs for Reference

What is Hadoop MapReduce primarily used for?
a. Real-time data processing
b. Batch processing of large datasets
c. Stream processing
d. In-memory data processing
Answer: b. Batch processing of large datasetseasyexamnotes+1
Which two components are required for a MapReduce job?
a. NameNode and DataNode
b. JobTracker and TaskTracker
c. ResourceManager and NodeManager
d. Mapper and Reducer
Answer: d. Mapper and Reducerfreshersnow+1
What is the function of the Mapper in MapReduce?
a. Aggregates intermediate results
b. Converts input data into key-value pairs
c. Performs final calculation
d. Divides data blocks
Answer: b. Converts input data into key-value pairsfreshersnow
What is the final step in a typical MapReduce cycle?
a. Mapping
b. Shuffling
c. Sorting
d. Reducing
Answer: d. Reducingcareerride+1
What ensures failure recovery in MapReduce processing?
a. Checkpoints
b. Fault tolerance
c. Data deduplication
d. Stream processing
Answer: b. Fault toleranceeasyexamnotes+1
What is the task of the Reducer in MapReduce?
a. Splits data blocks
b. Aggregates key-value pairs
c. Prepares metadata
d. Encrypts the output
Answer: b. Aggregates key-value pairsfreshersnow
Which term describes the phase where data is rearranged between Map and Reduce?
a. Partitioning
b. Shuffling
c. Serialization
d. Streaming
Answer: b. Shufflingcareerride
Which programming model is used by Hadoop for data processing?
a. Event-driven
b. MapReduce
c. Trigger-based
d. SQL-based
Answer: b. MapReduceeasyexamnotes+1
What is emitted as output by Mapper?
a. Strings
b. Key-value pairs
c. Individual values
d. Raw files
Answer: b. Key-value pairscareerride+1
What handles job scheduling and resource monitoring in Hadoop MapReduce?
a. TaskScheduler
b. JobTracker
c. DataNode
d. BlockManager
Answer: b. JobTrackerwhizlabs
Which of the following is a key advantage of MapReduce?
a. Low latency
b. In-memory processing
c. Fault tolerance
d. Real-time responsiveness
Answer: c. Fault toleranceeasyexamnotes+1
What kind of datasets is MapReduce designed for?
a. Small datasets
b. Medium datasets
c. Large datasets
d. Data streams
Answer: c. Large datasetsfreshersnow+1
Which function groups values by key in MapReduce?
a. Mapper
b. Partition
c. Combiner
d. Reducer
Answer: d. Reducerfreshersnow
What is a Combiner in MapReduce?
a. Optimizes output format
b. Local reducer to minimize data transfer
c. Sorts input data
d. Encrypts intermediate results
Answer: b. Local reducer to minimize data transfercareerride
Which file is responsible for storing reporting metrics in Hadoop?
a. core-site.xml
b. hdfs-site.xml
c. hadoop-metrics.properties
d. logs.xml
Answer: c. hadoop-metrics.propertiesprojectpro
Which input format is the default in MapReduce?
a. SequenceFileInputFormat
b. KeyValueInputFormat
c. TextInputFormat
d. DBInputFormat
Answer: c. TextInputFormatprojectpro
Which node executes the main MapReduce job?
a. DataNode
b. NameNode
c. JobTracker
d. ResourceManager
Answer: c. JobTrackerwhizlabs
What is output by the Reducer?
a. Intermediate values
b. Final key-value pairs
c. Raw data
d. Only values
Answer: b. Final key-value pairsfreshersnow
What is the function of the Partitioner in MapReduce?
a. Assigns tasks to nodes
b. Decides reducer data distribution
c. Compresses the output
d. Monitors memory
Answer: b. Decides reducer data distributionupgrad
How are intermediate data sorted in MapReduce?
a. By Mapper
b. By Reducer
c. During Shuffle phase
d. Before Map phase
Answer: c. During Shuffle phasecareerride
In which phase is data grouped by key?
a. Mapping
b. Combining
c. Reducing
d. Shuffle and Sort
Answer: d. Shuffle and Sortcareerride
Which node manages HDFS data blocks?
a. NameNode
b. SecondaryNameNode
c. DataNode
d. TaskTracker
Answer: c. DataNodewhizlabs
What does the input to a Mapper look like?
a. Line numbers only
b. Key-value pair from input split
c. File pointers
d. URLs
Answer: b. Key-value pair from input splitfreshersnow
What are the benefits of using Combiners?
a. Increase network traffic
b. Reduce local aggregation
c. Decrease local aggregation
d. Reduce network traffic
Answer: d. Reduce network trafficcareerride
Which principle enables scalability in MapReduce?
a. Vertical scaling
b. Parallel processing
c. In-memory caching
d. Indexing
Answer: b. Parallel processingfreshersnow
What describes the schema of MapReduce data?
a. Schema-on-write
b. Schema-on-read
c. Static schema
d. JSON only
Answer: b. Schema-on-readupgrad
Which of the following best defines a MapReduce job?
a. A group of related tasks
b. An entire Hadoop cluster
c. A collection of Map and Reduce tasks
d. A sequence of jobs
Answer: c. A collection of Map and Reduce tasksupgrad+1
Which phase follows Mapping?
a. Shuffling
b. Job initialization
c. Reducing
d. Launching
Answer: a. Shufflingcareerride
How is data passed from Mapper to Reducer?
a. As a flat file
b. As unsorted lists
c. As partitioned, shuffled, and sorted key-value pairs
d. As images
Answer: c. As partitioned, shuffled, and sorted key-value pairsfreshersnow+1
Which type of storage is used in MapReduce for intermediate data?
a. HDFS
b. In-memory cache
c. Local disk
d. Cloud storage
Answer: c. Local diskupgrad+1
What happens if a task fails in MapReduce?
a. Whole job fails
b. Task is resumed on a different node
c. Cluster restarts
d. Data is deleted
Answer: b. Task is resumed on a different nodeeasyexamnotes+1
Which Hadoop node monitors the individual Map and Reduce tasks?
a. JobTracker
b. DataNode
c. NameNode
d. TaskTracker
Answer: d. TaskTrackerwhizlabs
Which is a typical output format for MapReduce jobs?
a. Structured records
b. Plain text files
c. Images
d. XML only
Answer: b. Plain text filesfreshersnow
Which of the following would you use to test MapReduce code logic?
a. GUI debugger
b. Small test datasets
c. SSH shell
d. Visualization tool
Answer: b. Small test datasetsupgrad
Which feature allows users to define job-specific metrics in MapReduce?
a. Debuggers
b. Hadoop counters
c. DataNode monitor
d. Log files
Answer: b. Hadoop countersupgrad
What must each Mapper class extend in Hadoop?
a. java.io.Serializable
b. org.apache.hadoop.mapreduce.Mapper
c. java.util.Hashtable
d. org.apache.hadoop.util.Tool
Answer: b. org.apache.hadoop.mapreduce.Mapperadaface
Which programming languages are most common for writing MapReduce jobs?
a. Java and Python
b. C++ and Perl
c. SQL only
d. HTML
Answer: a. Java and Pythonadaface+1
Which one optimizes task distribution to improve efficiency?
a. Random partitioner
b. Custom partitioner
c. Duplicate removal
d. Load balancer only
Answer: b. Custom partitionerupgrad
Which ensures all values for a key are processed by a single reducer?
a. Shuffling
b. Combiner
c. Partitioning
d. Splitting
Answer: c. Partitioningupgrad
Which of these is NOT a fault-tolerant feature?
a. Data replication
b. Automatic task recovery
c. Task assignment retries
d. Manual user intervention for every failure
Answer: d. Manual user intervention for every failureeasyexamnotes+1
Which makes MapReduce scalable?
a. Centralized data storage only
b. Horizontal cluster scaling
c. GPU acceleration only
d. Manual scaling
Answer: b. Horizontal cluster scalingupgrad+1
Why is MapReduce not suitable for real-time analytics?
a. Too expensive
b. In-memory only
c. High batch processing latency
d. Uses SQL only
Answer: c. High batch processing latencyupgrad+1
Which handles network and disk failures in MapReduce?
a. Application logs
b. YARN or JobTracker
c. Line numbers
d. File rename
Answer: b. YARN or JobTrackerwhizlabs+1
What is the key requirement for writing MapReduce programs?
a. Must run on Spark
b. Input/output as key-value pairs
c. Real-time output generation
d. User authentication
Answer: b. Input/output as key-value pairsfreshersnow
During which phase can the records be grouped by common key values?
a. Map
b. Combine
c. Reduce
d. Shuffle and Sort
Answer: d. Shuffle and Sortcareerride
Which output file is the default from Reducer?
a. _SUCCESS only
b. No file
c. part-r-00000
d. cluster.log
Answer: c. part-r-00000adaface+1
Which MapReduce property controls job progress reporting?
a. mapreduce.job.progress
b. fs.defaultFS
c. hadoop-metrics.properties
d. reduce.tasks
Answer: c. hadoop-metrics.propertiesprojectpro
Which is NOT a valid MapReduce function?
a. Map
b. Reduce
c. Filter
d. Combine
Answer: c. Filtercareerride
Which environment variable informs MapReduce jobs about cluster size?
a. HADOOP_HOME
b. HADOOP_CONF_DIR
c. HADOOP_CLASSPATH
d. mapreduce.tasktracker.tasks.maximum
Answer: d. mapreduce.tasktracker.tasks.maximumupgrad
Which step occurs before Reduce tasks begin?
a. Output writing
b. Data shuffling and sorting
c. Result compression
d. Counter resetting
Answer: b. Data shuffling and sortingcareerride+1

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