Hadoop Distributed File System (HDFS) DATA-SCIENCE-OPTIMIZE Practice Questions (Page 4)

Questions 16–20

1. 16foundation · easy

   Which HDFS configuration parameter controls the default block size for new files?

   • Adfs.replication
   • Bdfs.blocksize
   • Cdfs.namenode.name.dir
   • Ddfs.datanode.data.dir
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2. 17application · medium

   A data analyst is running a MapReduce job that reads a large file from HDFS. During the job, one of the DataNodes hosting a block replica fails. The job continues to run successfully. Which HDFS mechanism allowed the job to complete without interruption?

   • AThe Secondary NameNode took over the failed DataNode's role and served the block.
   • BThe client read the block from a replica on another DataNode after detecting the failure.
   • CThe NameNode immediately re-replicated the lost block to a new DataNode before the job read it.
   • DThe job was automatically restarted from the beginning on a different set of DataNodes.
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4. 18foundation · easy

   What is the default block size for HDFS in a typical modern Hadoop distribution (e.g., Apache Hadoop 2.x/3.x)?

   • A256 MB
   • B64 MB
   • C128 MB
   • D1 GB
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5. 19foundation · easy

   In HDFS write operation, after the client sends the first block to the first DataNode, what happens next?

   • AThe client sends the same block to all DataNodes simultaneously
   • BThe first DataNode writes the block and then sends an acknowledgment back to the client
   • CThe NameNode stores the block data and then distributes it to DataNodes
   • DThe first DataNode replicates the block to the second DataNode, which replicates to the third, forming a pipeline
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6. 20expert · hard

   An HDFS cluster is experiencing slow write performance. The administrator suspects the issue is related to the write pipeline. The cluster has 10 DataNodes, and the default replication factor is 3. Which configuration change is most likely to improve write throughput?

   • AReduce the replication factor to 2.
   • BDecrease the block size to 64 MB.
   • CIncrease the replication factor to 5.
   • DIncrease the number of DataNodes in the cluster.
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