Cloudera Certified Administrator for Apache Hadoop CDH4 Sample Questions:

1. Which two occur when individual blocks are returned to DATANODE on a cluster local filesystem?

A) A metadata file is return to the datanode containing all the other node locations in the namespace
B) The datanode runs a block scanner datablock scanner to verify the return blocks.
C) A metadata file is written to the datanode containing the checksums for each block
D) The datanode writes a metadata file with the name of the file the block is associated with
E) The datanode updates it's log of checkum verification

2. You observe that the number of spilled records from map tasks for exceeds the number of map output records. You child heap size is 1 GB and your io.sort.mb value is set to 100MB. How would you tune your io.sort.mb value to achieve maximum memory to disk I/O ratio?

A) Increase the IO.sort.mb as high you can, as close to 1GB as possible.
B) Tune 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.
C) Decrease the io.sort.mb value below 100M
D) For 1GB child heap size an io.sort.mb of 128MB will always maximum memory to disk I/O.

3. Your running a hadoop cluster with a name node on the host mynamenode.
What are two ways you can determine available HDFS space in your cluster?

A) Run hadoop dfsadmin - report and locate the DFS remaming value
B) Run hadoop DFSAdmin -spaceQuota and subtract DFS used % from configured capacity
C) Run hadoop fs -du / and locate the dfs remaining value
D) Connect to http://mynamenode:50070/and locate the dfs remaining value

4. You have cluster running with the FIFO Scheduler enabled. You submit a large job A to the cluster, which you expect to run for one hour. Then, you submit job B to cluster, which you expect to run a couple of minutes only.
You submit both jobs with the same priority.
Which two best describes how the FIFO Scheduler arbitrates the cluster resources for a job and its tasks?

A) Because there is more then a single job on the cluster, the FIFO Scheduler will enforce a limit on the percentage of resources allocated to a particular job at any given time.
B) Given Jobs A and B submitted in that order, all tasks from job A are guaranteed to finish before all tasks from job B.
C) The order of execution of tasks within a job may vary.
D) The FIFO Schedule will pass an exception back to the client when Job B is submitted, since all slots on the cluster are in use.
E) Tasks are scheduled in the order of their jobs' submission.
F) The FIFO Scheduler will give, on average, equal share of the cluster resources over the job lifecycle.

5. You set the value of dfs.block.size to 64MB in hdfs-site.xml on a client machine, but you set the same property to 128MB on your clusters name node. What happens when the client writes a file to HDFS?

A) The file will be written successfully with a block size of 64MB but client attempting to read the file will fail because the namenode believes the blocks to be 128MB in size
B) An execution will be thrown when the client attempts to write the file, because the values are different.
C) A block size of 128MB will be used
D) A block size of 64MB will be used

Solutions: