Cloud Computing for Data Analysis - Midterm Exam - Practice Questions


1 . In relation to the MapReduce environment , files are stored in a Distributed File System . Which of the following statements is incorrect in relation to the Distributed File System ?

A. File is split into chunks usually 64MB in size
B. Each file chunk is replicated 3 times
C. The files are stored on a cluster of high performance data center machines
D. The machines on the cluster are connected via Ethernet


2 . Which of the following statements are example tasks for which MapReduce is suitable ?

i . ranking of Web pages by importance 
ii . searches in  friends   networks at social networking sites
iii . counting sales and grouping them by City or Region
iv . counting words in a text file

A . i . and iv .
B . ii . , and iii .
C . iii .  and  iv . 
D . i . , ii . , iii . , and iv . 


3 . What is the purpose of the Reduce Tasks in MapReduce environment ?

A . To reduce the logic of the Map function
B . Each Reducer produces some output , and the entire job is the union of what is produced by each Reducer 
C . To always Group or Aggregate the results from the Map function
D . The Reduce Tasks are not really needed , and can be omitted 


4 . What is the main need to have Hadoop ?

A . Need to process huge datasets on large clusters of computers
B . Need to build reliability in each application
C . Need for common open source platform
D . Need for replication of nodes 


5 . Which of the following statements are correct in Relation to Hadoop MapReduce , compared to traditional Relational Database Management System ( RDBMS ) ?

i . Hadoop MapReduce can handle much larger data size than traditional RDBMS
ii . Hadoop MapReduce provides both ‘ Interactive and Batch ‘ processing access
iii . traditional RDBMS provides updates of type  ‘ read and write many times ‘ , while Hadoop MapReduce provides ‘ write once read many times ‘
iv . traditional RDBMS has ‘ low ‘ integrity , while Hadoop MapReduce has ‘ high ‘ integrity 

A . i . and ii . 
B . i . and iii . 
C . ii . and iv .
D . iii . and iv .
E . all of the above 


6 . Which of the following statements is incorrect in relation to MapReduce ?

A . MapReduce is a programming model for efficient distributed computing
B . MapReduce allows for improved load balancing and faster recovery from failed tasks
C . The input to a Mapper is  a ( key , value ) pair
D . The number of Mappers , which are launched by Hadoop for a given job , is specified by the user 


7 . What are the main goals of Hadoop Distributed File System ( HDFS ) ?

i . can be built out of commodity hardware 
ii . very large distributed file system suitable for applications with large datasets
iii . optimized for streaming data and iterative algorithm applications
iv . highly fault tolerant 

A . i . , ii . , and iv . 
B . i . and iv . 
C . ii . and  iii .
D . iii . and iv . 
E . i . , ii . , iii . , and iv .


8 . Hadoop Distributed File System ( HDFS ) stores large files across machines on a cluster . To do that , it uses the concept of a block . Which of the statements below is incorrect in relation to the HDFS block ?

A . The size of the HDFS block is much larger than the size of regular operating system block 
B . A file larger than a single block is broken into multiple blocks , and each block can be stored on any of the disks on a cluster
C . The file metadata such as file name , owner of file , last modified date , are stored with the blocks 
D . To provide fault tolerance and availability , and insure against corrupted disks and machine failure , each block is replicated to a number of physically separate machines ( usually 3 )


9 . What is the primary purpose of the NameNode in Hadoop Distributed File System ( HDFS ) ?

A . To serve as a replication engine for HDFS blocks
B . To store and retrieve data blocks when requested by clients
C . To keep a copy of the merged namespace image and EditLog in case of failure
D . To manage the HDFS Namespace and Metadata , and keep an image of the entire file system namespace and map of blocks in memory