Cloudera CCA-410 問題集

質問 1：
What are the permissions of a file in HDFS with the following:rw-rw-r-x?
A. the owner and group cannot delete the file, but other can
B. HDFS runs in user space which makes all users with access to the namespace able to read, write and modify all files
C. the owner and group can read the file other can't
D. the owner and group can modify the contents of the file other can't
E. No one can modify the content of the file
正解：D
解説: (Topexam メンバーにのみ表示されます)

質問 2：
You has a cluster running with the Fail Scheduler enabled. There are currently no jobs running on the cluster you submit a job A, so that only job A is running on the cluster. A while later, you submit job B.
Now job A and Job B are running on the cluster al the same time. How will the Fair' Scheduler handle these two Jobs?
A. When job B gets submitted, Job A has to finish first, before job it can get scheduled.
B. When job B gets submitted, it will get assigned tasks, while job A continues to run with fewer tasks.
C. When job A gets submitted, it consumes all the task slot
D. When job A gets submitted, it doesn't consume all the task slot
正解：B
解説: (Topexam メンバーにのみ表示されます)

質問 3：
For each job, the Hadoop framework generates task log files. Where are Hadoop's task log files stored?
A. Cached on the local disk of the slave node running the task, then copied into HDFS.
B. On the local disk of the slave node running the task.
C. Cached on the local disk of the slave node running the task, then purged immediately upon task completion.
D. In HDFS, in the directory of the user who generates the job.
正解：B
解説: (Topexam メンバーにのみ表示されます)

質問 4：
What occurs when you run a hadoop job specifying output directory for job output which already exists in HDFS?
A. an error will occur after the mappers have completed but before any reducers begin to run because the output path must not exist during the shuffle and sort.
B. the job will run successfully output from the reducers will be placed in a directory called job output -1
C. An error will occur immediately because the output directory must not already exist.
D. the job will run successfully. Output from the reducers will override the contents of existing directory
正解：C
解説: (Topexam メンバーにのみ表示されます)

質問 5：
Your cluster has 9 slave nodes. The cluster block size is set to 128 MB and it's replication factor set to three.
How will the hadoop framework distribute block writes from a reducer into HDFS from a reducer outputting a 300MB file?
A. All 9 nodes will each receive exactly one block
B. The 9 blocks will be return to 3 nodes, such that each of the three get's one copy of each block
C. The 9 blocks will be return randomly to the nodes; some may receive multiple blocks some may receive none
D. The node on which the reducer is running will receive one copy of the each block. The other replicas will be placed on other nodes in the cluster
E. Reducer don't write blocks into HDFS
正解：C
解説: (Topexam メンバーにのみ表示されます)

質問 6：
Your Hadoop cluster contains nodes in three racks. Choose which scenario results if you leave the dfs.hosts property in the NameNode's configuration file empty (blank)?
A. Any machine running the DataNode daemon can immediately join the cluster.
B. Presented with a blank dfs.hosts property, the NameNode will permit DataNodes specified in mapred.hosts to join the cluster.
C. No new can be added to the cluster until you specify them in the dfs.hosts file.
D. The NameNode will update dfs.hosts property to include machines running the DataNode daemon on the next NameNode reboot or with a dfsadmin -refreshNodes.
正解：C
解説: (Topexam メンバーにのみ表示されます)

質問 7：
What four functions do scheduling algorithms perform on hadoop cluster?
A. Reduce the job latencies in environment with multiple jobs of different sizes
B. allow short jobs to complete even when large, long jobs (consuming a lot of resources are running)
C. Run jobs at periodic times of the day
D. Allow multiple users to share clusters in a predictable policy-guided manner
E. Reduce the total amount of computation necessary to complete a job.
F. Ensure data locality by ordering map tasks so that they run on data local maps slots
G. support the implementation of service-level agreements for multiple cluster users
正解：A,B,C,E
解説: (Topexam メンバーにのみ表示されます)