Audit logging in Hadoop - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Audit log file content after enabling HDFS audit logging

You enabled audit logging in HDFS by setting dfs.namenode.audit.log.enabled=true in hdfs-site.xml. After restarting the NameNode, you perform a file read operation. What will you find in the audit log file?

A A summary of all file system operations without user details.

B Only error messages related to failed operations.

C No entries until the DataNode logs are checked.

D A log entry showing the user, operation type (READ), file path, and timestamp.

💡 Hint

Audit logs record detailed info about each operation including user and action.

When audit logging is enabled in HDFS, each file system operation like READ or WRITE is logged with details such as user, operation type, file path, and timestamp in the audit log file.

❓ Configuration

intermediate

Configuring audit logging in Hadoop's hdfs-site.xml

Which configuration snippet correctly enables audit logging for the NameNode in Hadoop?

A

<property>
  <name>dfs.namenode.audit.log.enabled</name>
  <value>true</value>
</property>

B

<property>
  <name>dfs.datanode.audit.log.enabled</name>
  <value>true</value>
</property>

C

<property>
  <name>dfs.audit.logging</name>
  <value>enabled</value>
</property>

D

<property>
  <name>dfs.namenode.audit.enable</name>
  <value>yes</value>
</property>

💡 Hint

The correct property name is specific and must be exact.

The correct property to enable audit logging on the NameNode is dfs.namenode.audit.log.enabled set to true. Other options are incorrect property names or values.

❓ Troubleshoot

advanced

Why are no audit logs generated despite enabling audit logging?

You set dfs.namenode.audit.log.enabled=true and restarted the NameNode, but no audit logs appear in the expected directory. What is the most likely cause?

A The property must be set in <code>core-site.xml</code>, not <code>hdfs-site.xml</code>.

B Audit logging only works on DataNodes, not NameNodes.

C The NameNode user does not have write permission to the audit log directory.

D Audit logs are only generated if the cluster is in safe mode.

💡 Hint

Check file system permissions for the log directory.

If the NameNode process user lacks write permission to the audit log directory, logs cannot be created even if audit logging is enabled.

✅ Best Practice

advanced

Best practice for managing audit log file size in Hadoop

What is the recommended way to manage audit log file size to prevent disk space issues?

A Configure log rotation using tools like logrotate to archive and compress old audit logs.

B Store audit logs on the same disk as HDFS data for faster access.

C Manually delete audit logs once a week without backups.

D Disable audit logging during peak hours to reduce log size.

💡 Hint

Automated log rotation helps keep logs manageable and safe.

Using log rotation tools to archive and compress audit logs regularly is the best practice to prevent disk space exhaustion and maintain logs safely.

🔀 Workflow

expert

Sequence of steps to enable and verify audit logging in Hadoop HDFS

Arrange the following steps in the correct order to enable and verify audit logging on the Hadoop NameNode.

A 3,1,2,4

B 1,2,3,4

C 1,3,2,4

D 2,1,3,4

💡 Hint

Configuration changes require restart before testing and verification.

First configure audit logging, then restart NameNode to apply changes, perform an operation to generate logs, and finally check the audit log file.