NEW QUESTION 1
Assume you have a file named foo.txt in your local directory. You issue the following three commands:
Hadoop fs –mkdir input
Hadoop fs –put foo.txt input/foo.txt
Hadoop fs –put foo.txt input
What happens when you issue the third command?

• A. The write succeeds, overwriting foo.txt in HDFS with no warning
• B. The file is uploaded and stored as a plain file named input
• C. You get a warning that foo.txt is being overwritten
• D. You get an error message telling you that foo.txt already exists, and asking you if you would like to overwrite it.
• E. You get a error message telling you that foo.txt already exist
• F. The file is not written to HDFS
• G. You get an error message telling you that input is not a directory
• H. The write silently fails

Answer: CE

NEW QUESTION 2
You observed that the number of spilled records from Map tasks far exceeds the number of map output records. Your child heap size is 1GB and your io.sort.mb value is set to 1000MB. How would you tune your io.sort.mb value to achieve maximum memory to disk I/O ratio?

• A. For a 1GB child heap size an io.sort.mb of 128 MB will always maximize memory to disk I/O
• B. Increase the io.sort.mb to 1GB
• C. Decrease the io.sort.mb value to 0
• D. Tune the io.sort.mb value until you observe that the number of spilled records equals (or is as close to equals) the number of map output records.

Answer: D

NEW QUESTION 3
You are configuring your cluster to run HDFS and MapReducer v2 (MRv2) on YARN. Which two daemons needs to be installed on your cluster’s master nodes?(Choose two)

• A. HMaster
• B. ResourceManager
• C. TaskManager
• D. JobTracker
• E. NameNode
• F. DataNode

Answer: BE

NEW QUESTION 4
Your Hadoop cluster contains nodes in three racks. You have not configured the dfs.hosts property in the NameNode’s configuration file. What results?

• A. The NameNode will update the dfs.hosts property to include machines running the DataNode daemon on the next NameNode reboot or with the command dfsadmin–refreshNodes
• B. No new nodes can be added to the cluster until you specify them in the dfs.hosts file
• C. Any machine running the DataNode daemon can immediately join the cluster
• D. Presented with a blank dfs.hosts property, the NameNode will permit DataNodes specified in mapred.hosts to join the cluster

Answer: C

NEW QUESTION 5
Your Hadoop cluster is configuring with HDFS and MapReduce version 2 (MRv2) on YARN. Can you configure a worker node to run a NodeManager daemon but not a DataNode daemon and still have a functional cluster?

• A. Ye
• B. The daemon will receive data from the NameNode to run Map tasks
• C. Ye
• D. The daemon will get data from another (non-local) DataNode to run Map tasks
• E. Ye
• F. The daemon will receive Map tasks only
• G. Ye
• H. The daemon will receive Reducer tasks only

Answer: B

NEW QUESTION 6
You are configuring a server running HDFS, MapReduce version 2 (MRv2) on YARN running Linux. How must you format underlying file system of each DataNode?

• A. They must be formatted as HDFS
• B. They must be formatted as either ext3 or ext4
• C. They may be formatted in any Linux file system
• D. They must not be formatted - - HDFS will format the file system automatically

Answer: B

NEW QUESTION 7
Identify two features/issues that YARN is designated to address:(Choose two)

• A. Standardize on a single MapReduce API
• B. Single point of failure in the NameNode
• C. Reduce complexity of the MapReduce APIs
• D. Resource pressure on the JobTracker
• E. Ability to run framework other than MapReduce, such as MPI
• F. HDFS latency

Answer: DE

Explanation: Reference:http://www.revelytix.com/?q=content/hadoop-ecosystem(YARN, first para)

NEW QUESTION 8
Which two features does Kerberos security add to a Hadoop cluster?(Choose two)

• A. User authentication on all remote procedure calls (RPCs)
• B. Encryption for data during transfer between the Mappers and Reducers
• C. Encryption for data on disk (“at rest”)
• D. Authentication for user access to the cluster against a central server
• E. Root access to the cluster for users hdfs and mapred but non-root access for clients

Answer: AD

NEW QUESTION 9
You have installed a cluster HDFS and MapReduce version 2 (MRv2) on YARN. You have no dfs.hosts entry(ies) in your hdfs-site.xml configuration file. You configure a new worker node by setting fs.default.name in its configuration files to point to the NameNode on your cluster, and you start the DataNode daemon on that worker node. What do you have to do on the cluster to allow the worker node to join, and start sorting HDFS blocks?

• A. Without creating a dfs.hosts file or making any entries, run the commands hadoop.dfsadmin-refreshModes on the NameNode
• B. Restart the NameNode
• C. Creating a dfs.hosts file on the NameNode, add the worker Node’s name to it, then issue the command hadoop dfsadmin –refresh Nodes = on the Namenode
• D. Nothing; the worker node will automatically join the cluster when NameNode daemon is started

Answer: A

NEW QUESTION 10
Given:

You want to clean up this list by removing jobs where the State is KILLED. What command you enter?

• A. Yarn application –refreshJobHistory
• B. Yarn application –kill application_1374638600275_0109
• C. Yarn rmadmin –refreshQueue
• D. Yarn rmadmin –kill application_1374638600275_0109

Answer: B

Explanation: Reference:http://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.1-latest/bk_using-apache-hadoop/content/common_mrv2_commands.html

NEW QUESTION 11
You decide to create a cluster which runs HDFS in High Availability mode with automatic failover, using Quorum Storage. What is the purpose of ZooKeeper in such a configuration?

• A. It only keeps track of which NameNode is Active at any given time
• B. It monitors an NFS mount point and reports if the mount point disappears
• C. It both keeps track of which NameNode is Active at any given time, and manages the Edits fil
• D. Which is a log of changes to the HDFS filesystem
• E. If only manages the Edits file, which is log of changes to the HDFS filesystem
• F. Clients connect to ZooKeeper to determine which NameNode is Active

Answer: A

Explanation: Reference: Reference:http://www.cloudera.com/content/cloudera-content/cloudera-docs/CDH4/latest/PDF/CDH4-High-Availability-Guide.pdf(page 15)

NEW QUESTION 12
You want to node to only swap Hadoop daemon data from RAM to disk when absolutely necessary. What should you do?

• A. Delete the /dev/vmswap file on the node
• B. Delete the /etc/swap file on the node
• C. Set the ram.swap parameter to 0 in core-site.xml
• D. Set vm.swapfile file on the node
• E. Delete the /swapfile file on the node

Answer: D

NEW QUESTION 13
You want to understand more about how users browse your public website. For example, you want to know which pages they visit prior to placing an order. You have a server farm of 200 web servers hosting your website. Which is the most efficient process to gather these web server across logs into your Hadoop cluster analysis?

• A. Sample the web server logs web servers and copy them into HDFS using curl
• B. Ingest the server web logs into HDFS using Flume
• C. Channel these clickstreams into Hadoop using Hadoop Streaming
• D. Import all user clicks from your OLTP databases into Hadoop using Sqoop
• E. Write a MapReeeduce job with the web servers for mappers and the Hadoop cluster nodes for reducers

Answer: B

Explanation: Apache Flume is a service for streaming logs into Hadoop.
Apache Flume is a distributed, reliable, and available service for efficiently collecting, aggregating, and moving large amounts of streaming data into the Hadoop Distributed File System (HDFS). It has a simple and flexible architecture based on streaming data flows; and is robust and fault tolerant with tunable reliability mechanisms for failover and recovery.

NEW QUESTION 14
Choose three reasons why should you run the HDFS balancer periodically?(Choose three)

• A. To ensure that there is capacity in HDFS for additional data
• B. To ensure that all blocks in the cluster are 128MB in size
• C. To help HDFS deliver consistent performance under heavy loads
• D. To ensure that there is consistent disk utilization across the DataNodes
• E. To improve data locality MapReduce

Answer: CDE

Explanation: http://www.quora.com/Apache-Hadoop/It-is-recommended-that-you-run-the-HDFS-balancer-periodically-Why-Choose-3

NEW QUESTION 15
Which YARN process run as “container 0” of a submitted job and is responsible for resource qrequests?

• A. ApplicationManager
• B. JobTracker
• C. ApplicationMaster
• D. JobHistoryServer
• E. ResoureManager
• F. NodeManager

Answer: C

NEW QUESTION 16
On a cluster running MapReduce v2 (MRv2) on YARN, a MapReduce job is given a directory of 10 plain text files as its input directory. Each file is made up of 3 HDFS blocks. How many Mappers will run?

• A. We cannot say; the number of Mappers is determined by the ResourceManager
• B. We cannot say; the number of Mappers is determined by the developer
• C. 30
• D. 3
• E. 10
• F. We cannot say; the number of mappers is determined by the ApplicationMaster

Answer: E

NEW QUESTION 17
A user comes to you, complaining that when she attempts to submit a Hadoop job, it fails. There is a Directory in HDFS named /data/input. The Jar is named j.jar, and the driver class is named DriverClass.
She runs the command:
Hadoop jar j.jar DriverClass /data/input/data/output The error message returned includes the line:
PriviligedActionException as:training (auth:SIMPLE) cause:org.apache.hadoop.mapreduce.lib.input.invalidInputException:
Input path does not exist: file:/data/input What is the cause of the error?

• A. The user is not authorized to run the job on the cluster
• B. The output directory already exists
• C. The name of the driver has been spelled incorrectly on the command line
• D. The directory name is misspelled in HDFS
• E. The Hadoop configuration files on the client do not point to the cluster

Answer: A