Cloudera CCD-410 Cloudera Certified Developer for Apache Hadoop (CCDH) Practice Test 2 | Practice Test / Quiz / MCQs

2. Assuming default settings, which best describes the order of data provided to a reducer's reduce method:

Neither keys nor values are in any predictable order.The keys given to a reducer are in sorted order but the values associated with each key are in no predictable orderThe keys given to a reducer aren't in a predictable order, but the values associated with those keys always are.Both the keys and values passed to a reducer always appear in sorted order.

3. Given a directory of files with the following structure: line number, tab character, string: Example: 1abialkjfjkaoasdfjksdlkjhqweroij 2kadfjhuwqounahagtnbvaswslmnbfgy 3kjfteiomndscxeqalkzhtopedkfsikj You want to send each line as one record to your Mapper. Which InputFormat should you use to complete the line: conf.setInputFormat (____.class) ; ?

KeyValueFileInputFormatSequenceFileInputFormatSequenceFileAsTextInputFormatBDBInputFormat

4. You have user profile records in your OLPT database, that you want to join with web logs you have already ingested into the Hadoop file system. How will you obtain these user records?

Hive LOAD DATA commandSqoop importPig LOAD commandHDFS command

5. In the reducer, the MapReduce API provides you with an iterator over Writable values. What does calling the next () method return?

It returns a reference to a Writable object. The API leaves unspecified whether this is a reused object or a new object.It returns a reference to a Writable object from an object pool.It returns a reference to the same Writable object each time, but populated with different data.It returns a reference to a different Writable object time.

6. What data does a Reducer reduce method process?

All the data in a single input file.All data for a given key, regardless of which mapper(s) produced it.All data for a given value, regardless of which mapper(s) produced it.All data produced by a single mapper.

7. In a MapReduce job, you want each of your input files processed by a single map task. How do you configure a MapReduce job so that a single map task processes each input file regardless of how many blocks the input file occupies?

Write a custom MapRunner that iterates over all key-value pairs in the entire file.Write a custom FileInputFormat and override the method isSplitable to always return false.Set the number of mappers equal to the number of input files you want to process.Increase the parameter that controls minimum split size in the job configuration.

8. Your client application submits a MapReduce job to your Hadoop cluster. Identify the Hadoop daemon on which the Hadoop framework will look for an available slot schedule a MapReduce operation.

JobTrackerDataNodeTaskTrackerNameNode

9. How are keys and values presented and passed to the reducers during a standard sort and shuffle phase of MapReduce?

Keys are presented to a reducer in random order; values for a given key are not sorted.Keys are presented to reducer in sorted order; values for a given key are sorted in ascending order.Keys are presented to a reducer in random order; values for a given key are sorted in ascending order.Keys are presented to reducer in sorted order; values for a given key are not sorted.

10. Indentify which best defines a SequenceFile?

A SequenceFile contains a binary encoding of an arbitrary number of homogeneous Writable objectsA SequenceFile contains a binary encoding of an arbitrary number of heterogeneous Writable objectsA SequenceFile contains a binary encoding of an arbitrary number key-value pairs. Each key must be the same type. Each value must be the same type. A SequenceFile contains a binary encoding of an arbitrary number of WritableComparable objects, in sorted order.

11. Which process describes the lifecycle of a Mapper?

The TaskTracker spawns a new Mapper to process all records in a single input split.The JobTracker spawns a new Mapper to process all records in a single file.The JobTracker calls the TaskTracker's configure () method, then its map () method and finally its close () method.The TaskTracker spawns a new Mapper to process each key-value pair.

12. What is a SequenceFile?

A SequenceFile contains a binary encoding of an arbitrary number of WritableComparable objects, in sorted order.A SequenceFile contains a binary encoding of an arbitrary number key-value pairs. Each key must be the same type. Each value must be same type.A SequenceFile contains a binary encoding of an arbitrary number of heterogeneous writable objects.A SequenceFile contains a binary encoding of an arbitrary number of homogeneous writable objects.

13. You use the hadoop fs put command to write a 300 MB file using and HDFS block size of 64 MB. Just after this command has finished writing 200 MB of this file, what would another user see when trying to access this life?

They would see the current of the file through the last completed block.They would see Hadoop throw an ConcurrentFileAccessException when they try to access this file.They would see no content until the whole file written and closed.They would see the current state of the file, up to the last bit written by the command.

14. What types of algorithms are difficult to express in MapReduce v1 (MRv1)?

Algorithms that require global, sharing states.Algorithms that require applying the same mathematical function to large numbers of individual binary records.Large-scale graph algorithms that require one-step link traversal.Relational operations on large amounts of structured and semi-structured data.

15. Identify the MapReduce v2 (MRv2 / YARN) daemon responsible for launching application containers and monitoring application resource usage?

ApplicationMasterApplicationMasterServiceNodeManagerResourceManager

16. Your cluster's HDFS block size in 64MB. You have directory containing 100 plain text files, each of which is 100MB in size. The InputFormat for your job is TextInputFormat. Determine how many Mappers will run?

64200640100

17. You want to run Hadoop jobs on your development workstation for testing before you submit them to your production cluster. Which mode of operation in Hadoop allows you to most closely simulate a production cluster while using a single machine?

Run the DataNode, TaskTracker, NameNode and JobTracker daemons on a single machine.Run all the nodes in your production cluster as virtual machines on your development workstation.Run the hadoop command with the jt local and the fs file:///options.Run simldooop, the Apache open-source software for simulating Hadoop clusters.

18. To process input key-value pairs, your mapper needs to lead a 512 MB data file in memory. What is the best way to accomplish this?

Place the data file in the DataCache and read the data into memory in the configure method of the mapper.Serialize the data file, insert in it the JobConf object, and read the data into memory in the configure method of the mapper.Place the data file in the DistributedCache and read the data into memory in the configure method of the mapper.Place the data file in the DistributedCache and read the data into memory in the map method of the mapper.

19. A client application creates an HDFS file named foo.txt with a replication factor of 3. Identify which best describes the file access rules in HDFS if the file has a single block that is stored on data nodes A, B and

Each data node stores a copy of the file in the local file system with the same name as the HDFS file.Each data node locks the local file to prohibit concurrent readers and writers of the file.A.The file will be marked as corrupted if data node B fails during the creation of the file.The file can be accessed if at least one of the data nodes storing the file is available.

20. MapReduce v2 (MRv2/YARN) splits which major functions of the JobTracker into separate daemons?

Job coordination between the ResourceManager and NodeManager Heath states checks (heartbeats)Launching tasksResource management / Job scheduling/monitoring

21. Which best describes what the map method accepts and emits?

It accepts a single key-value pairs as input and can emit any number of key-value pair as output, including zero.It accepts a single key-value pairs as input and can emit only one key-value pair as output.It accepts a list key-value pairs as input and can emit only one key-value pair as output.It accepts a single key-value pair as input and emits a single key and list of corresponding values as output.

22. You write MapReduce job to process 100 files in HDFS. Your MapReduce algorithm uses TextInputFormat: the mapper applies a regular expression over input values and emits key-values pairs with the key consisting of the matching text, and the value containing the filename and byte offset. Determine the difference between setting the number of reduces to one and settings the number of reducers to zero.

With zero reducers, all instances of matching patterns are gathered together in one file on HDFS. With one reducer, instances of matching patterns are stored in multiple files on HDFS.With zero reducers, no reducer runs and the job throws an exception. With one reducer, instances of matching patterns are stored in a single file on HDFS.There is no difference in output between the two settings.With zero reducers, instances of matching patterns are stored in multiple files on HDFS. With one reducer, all instances of matching patterns are gathered together in one file on HDFS.

23. You have a directory named jobdata in HDFS that contains four files: _first.txt, second.txt, .third.txt and #data.txt. How many files will be processed by the FileInputFormat.setInputPaths () command when it's given a path object representing this directory?

Two, file names with a leading period or underscore are ignoredThree, the pound sign is an invalid character for HDFS file namesFour, all files will be processedNone, the directory cannot be named jobdata

24. You wrote a map function that throws a runtime exception when it encounters a control character in input data. The input supplied to your mapper contains twelve such characters totals, spread across five file splits. The first four file splits each have two control characters and the last split has four control characters. Indentify the number of failed task attempts you can expect when you run the job with mapred.max.map.attempts set to 4:

You will have seventeen failed task attemptsYou will have twenty failed task attemptsYou will have five failed task attemptsYou will have forty-eight failed task attempts

25 Questions

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25 Questions

❤ If you liked Fatskills, consider supporting us by checking out The Life Manuals You Never Got.

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About | Explore | User Guide | Topics | Subjects | Doubt Solver | Career Aptitude Test | Answers | Free Tools | What Should We Know?
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Without work one finishes nothing. - Ralph Waldo Emerson
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