Big Data Hadoop Administrator Certification Exam 2026:
Professional Practice Test — HDFS, YARN, Hadoop Cluster
Management, Security, Performance Tuning & Troubleshooting —
190 Multiple-Choice Questions with Answers & Detailed Rationales
SECTION 1: Hadoop Fundamentals and Architecture (Questions 1–25)
Question 1
A system administrator is evaluating whether Hadoop is the appropriate platform for a new
workload. The workload involves frequent random updates to individual records and
requires strong ACID compliance at the row level. Which characteristic of HDFS makes it
LEAST suitable for this use case?
A. HDFS supports high-throughput sequential reads across large files
B. HDFS is optimized for write-once, read-many access patterns
C. HDFS replicates data across multiple nodes for fault tolerance
D. HDFS stores metadata separately from actual data blocks
Correct Answer: B
Explanation: HDFS is designed for write-once, read-many workloads; random row-level
updates are inefficient and better suited to RDBMS or HBase. Best practice: match storage
technology to access pattern.
Question 2
A Hadoop administrator is explaining the role of the NameNode to a junior engineer. Which
statement accurately describes the NameNode's primary responsibility?
,A. It stores the actual data blocks on local disk
B. It manages the file system namespace and block metadata
C. It performs MapReduce task scheduling across nodes
D. It replicates blocks between DataNodes during writes
Correct Answer: B
Explanation: The NameNode is the master that maintains namespace, directory tree, and
block locations; actual data resides on DataNodes. This separation enables scalability and
centralized metadata management.
Question 3
A DataNode in a production cluster has been marked as stale by the NameNode. What is the
MOST likely cause of this condition?
A. The DataNode's disk utilization exceeded 90%
B. The DataNode failed to send a heartbeat within the stale interval
C. The DataNode's block scanner detected a checksum error
D. The DataNode received more write requests than its threshold
Correct Answer: B
Explanation: StaleNodeInterval marks DataNodes that miss heartbeats as stale; they are
avoided for reads. Staleness indicates communication delay, not necessarily disk or
checksum issues.
Question 4
,A company wants to add a new DataNode to an existing Hadoop cluster. Which action must
the administrator take FIRST before the DataNode can join the cluster?
A. Format the NameNode metadata directory
B. Add the node's hostname to the include file and refresh nodes
C. Restart the ResourceManager service
D. Rebalance the existing blocks across the cluster
Correct Answer: B
Explanation: The include file (dfs.hosts) must list the new DataNode, then refreshNodes is
invoked so the NameNode recognizes it. Formatting NameNode would destroy metadata.
Question 5
Which component in Hadoop 2.x and later is responsible for resource management and
scheduling across applications?
A. NameNode
B. JobTracker
C. ResourceManager
D. NodeManager
Correct Answer: C
Explanation: YARN's ResourceManager is the cluster-level scheduler that allocates resources
to applications. JobTracker was the MapReduce v1 equivalent, now replaced by
ResourceManager and ApplicationMaster.
, Question 6
An administrator observes that the Secondary NameNode is running but the cluster still
experiences long restart times after a NameNode failure. What is the PRIMARY limitation of
the Secondary NameNode?
A. It cannot merge edit logs into the fsimage
B. It is not a hot standby and cannot take over NameNode duties
C. It stores a stale copy of the fsimage
D. It only works with federated NameNodes
Correct Answer: B
Explanation: The Secondary NameNode performs checkpointing but is not a failover
standby; HA requires a standby NameNode with shared edits. This distinction is critical for
availability planning.
Question 7
In HDFS, what is the default replication factor for a file when no explicit value is specified?
A. 1
B. 2
C. 3
D. 5
Correct Answer: C
Professional Practice Test — HDFS, YARN, Hadoop Cluster
Management, Security, Performance Tuning & Troubleshooting —
190 Multiple-Choice Questions with Answers & Detailed Rationales
SECTION 1: Hadoop Fundamentals and Architecture (Questions 1–25)
Question 1
A system administrator is evaluating whether Hadoop is the appropriate platform for a new
workload. The workload involves frequent random updates to individual records and
requires strong ACID compliance at the row level. Which characteristic of HDFS makes it
LEAST suitable for this use case?
A. HDFS supports high-throughput sequential reads across large files
B. HDFS is optimized for write-once, read-many access patterns
C. HDFS replicates data across multiple nodes for fault tolerance
D. HDFS stores metadata separately from actual data blocks
Correct Answer: B
Explanation: HDFS is designed for write-once, read-many workloads; random row-level
updates are inefficient and better suited to RDBMS or HBase. Best practice: match storage
technology to access pattern.
Question 2
A Hadoop administrator is explaining the role of the NameNode to a junior engineer. Which
statement accurately describes the NameNode's primary responsibility?
,A. It stores the actual data blocks on local disk
B. It manages the file system namespace and block metadata
C. It performs MapReduce task scheduling across nodes
D. It replicates blocks between DataNodes during writes
Correct Answer: B
Explanation: The NameNode is the master that maintains namespace, directory tree, and
block locations; actual data resides on DataNodes. This separation enables scalability and
centralized metadata management.
Question 3
A DataNode in a production cluster has been marked as stale by the NameNode. What is the
MOST likely cause of this condition?
A. The DataNode's disk utilization exceeded 90%
B. The DataNode failed to send a heartbeat within the stale interval
C. The DataNode's block scanner detected a checksum error
D. The DataNode received more write requests than its threshold
Correct Answer: B
Explanation: StaleNodeInterval marks DataNodes that miss heartbeats as stale; they are
avoided for reads. Staleness indicates communication delay, not necessarily disk or
checksum issues.
Question 4
,A company wants to add a new DataNode to an existing Hadoop cluster. Which action must
the administrator take FIRST before the DataNode can join the cluster?
A. Format the NameNode metadata directory
B. Add the node's hostname to the include file and refresh nodes
C. Restart the ResourceManager service
D. Rebalance the existing blocks across the cluster
Correct Answer: B
Explanation: The include file (dfs.hosts) must list the new DataNode, then refreshNodes is
invoked so the NameNode recognizes it. Formatting NameNode would destroy metadata.
Question 5
Which component in Hadoop 2.x and later is responsible for resource management and
scheduling across applications?
A. NameNode
B. JobTracker
C. ResourceManager
D. NodeManager
Correct Answer: C
Explanation: YARN's ResourceManager is the cluster-level scheduler that allocates resources
to applications. JobTracker was the MapReduce v1 equivalent, now replaced by
ResourceManager and ApplicationMaster.
, Question 6
An administrator observes that the Secondary NameNode is running but the cluster still
experiences long restart times after a NameNode failure. What is the PRIMARY limitation of
the Secondary NameNode?
A. It cannot merge edit logs into the fsimage
B. It is not a hot standby and cannot take over NameNode duties
C. It stores a stale copy of the fsimage
D. It only works with federated NameNodes
Correct Answer: B
Explanation: The Secondary NameNode performs checkpointing but is not a failover
standby; HA requires a standby NameNode with shared edits. This distinction is critical for
availability planning.
Question 7
In HDFS, what is the default replication factor for a file when no explicit value is specified?
A. 1
B. 2
C. 3
D. 5
Correct Answer: C
