HDFS practice questions



Set of questions & answers to test your introductory knowledge on Hadoop security concepts

1. HDFS stands for ____________.

    a. Hadoop Distributed Folder System
    b. Hadoop Distributed Feature System
    c. Hadoop Distributed File System
    d. Hadoop Direct File System

1. HDFS stands for ____________.

Answer: c.
Hadoop Distributed File System

Explanation: Hadoop uses a distributed file system inspired by Google File System. It is called Hadoop Distributed File System (HDFS).

2. Which command is used to upload files in Hadoop environment?

    a. Hadoop fs -ls
    b. Hadoop fs
    c. Hadoop fs –copyFromLocal source destination
    d. cp source destination

2. Which command is used to upload files in Hadoop environment?

Answer: c.
Hadoop fs –copyFromLocal source destination

Explanation: Invoke HDFS file system operations using Hadoop fs –command. For copying form local file system to HDFS, use Hadoop fs –copyFromLocal source destination

3. Which of the following parameters in the HDFS command is used for downloading the data from HDFS to Linux Filesystem?

    a. copyToLocal
    b. cp
    c. mv
    d. copyAtLocal

3. Which of the following parameters in the HDFS command is used for downloading the data from HDFS to Linux Filesystem?

Answer: a.
copyToLocal

Explanation: The command for downloading the data from HDFS to local file system is hadoop fs –copyToLocal source destination

4. What is the recommended data replication topology? (R=Rack, N=Node)

    a. R1N1, R2N1, R2N2
    b. R1N1, R1N2, R2N1
    c. R1N1, R1N1, R1N3
    d. R1N1, R2N1, R1N2

4. What is the recommended data replication topology? (R=Rack, N=Node)

Answer: a.
R1N1, R2N1, R2N2

Explanation: It is recommended that a block B1 is first written to Node N1 on Rack 1. A copy is then written on a Node N1 on different rack – Rack 2. The third and final copy of the block is written to the same rack as the second copy – Rack 2 – but a different node (N2, in this example).
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