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Akanksha
Akanksha

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Top 30 Logstash Interview Questions with Answers

1. What is Logstash?

a) A database management system
b) A data analysis tool
c) An open-source data collection and processing tool
d) An operating system
Answer: c) An open-source data collection and processing tool

2. Which company developed Logstash?

a) Microsoft
b) Google
c) Amazon
d) Elastic
Answer: d) Elastic

3. What is the primary purpose of Logstash?

a) Data visualization
b) Data collection and transformation
c) Data storage
d) Data encryption
Answer: b) Data collection and transformation

4. Which configuration file format does Logstash use?

a) XML
b) YAML
c) JSON
d) INI
Answer: c) JSON

5. Which input plugin is commonly used in Logstash for collecting log data from files?

a) jdbc
b) tcp
c) file
d) http
Answer: c) file

6. What is the purpose of Logstash's filter plugins?

a) To store data
b) To aggregate data
c) To transform and enrich data
d) To generate reports
Answer: c) To transform and enrich data

7. Which output plugin is often used to send data to Elasticsearch in Logstash?

a) csv
b) elasticsearch
c) stdout
d) s3
Answer: b) elasticsearch

8. What is the role of the "grok" filter in Logstash?

a) It's used for database queries
b) It parses unstructured log data into structured data
c) It sends data to external services
d) It encrypts data
Answer: b) It parses unstructured log data into structured data

9. Which protocol can Logstash use for log data ingestion?

a) FTP
b) HTTP
c) SMB
d) All of the above
Answer: d) All of the above

10. Which of the following is not a part of the ELK Stack, where Logstash is often used?

a) Elasticsearch
b) Kibana
c) Log4j
d) Beats
Answer: c) Log4j

11. What is the purpose of Logstash's "multiline" filter plugin?

a) To split log events into multiple lines
b) To combine multiple log lines into a single event
c) To encrypt log data
d) To filter out specific log lines
Answer: b) To combine multiple log lines into a single event

12. Which option is used to start Logstash with a specific configuration file?

a) --config-file
b) --start
c) --run
d) --logstash-config
Answer: a) --config-file

13. What is the primary role of Logstash's "date" filter plugin?

a) To filter log events by date
b) To extract and parse date-related information from log data
c) To generate random dates for log events
d) To sort log events by date
Answer: b) To extract and parse date-related information from log data

14. Which Logstash output plugin is used to send data to Amazon S3?

a) s3
b) elasticsearch
c) stdout
d) http
Answer: a) s3

15. In Logstash, what does the "codec" configuration option specify for an output plugin?

a) The type of encryption to be used
b) The character encoding for log data
c) The plugin's version
d) The target data destination
Answer: b) The character encoding for log data

16. What is the purpose of the "mutate" filter plugin in Logstash?

a) To add, remove, or rename fields in log events
b) To mutate the log data into binary format
c) To encrypt log events
d) To filter log events
Answer: a) To add, remove, or rename fields in log events

17. Which option is used to reload the Logstash configuration without stopping the Logstash process?

a) --restart
b) --reload
c) --refresh
d) --reset
Answer: b) --reload

18. Which input plugin is commonly used for collecting data from MySQL databases in Logstash?

a) file
b) jdbc
c) http
d) stdin
Answer: b) jdbc

19. In Logstash, what is the role of the "geoip" filter plugin?

a) To filter out geographic data from log events
b) To add geographic information to log events
c) To encrypt geographic data in log events
d) To plot geographic data on a map
Answer: b) To add geographic information to log events

20. What is the purpose of the "aggregate" filter plugin in Logstash?

a) To combine multiple Logstash instances
b) To aggregate and summarize log data
c) To encrypt log data
d) To split log events into multiple events
Answer: b) To aggregate and summarize log data

21. Which output plugin is used to send data to a syslog server in Logstash?

a) udp
b) syslog
c) elasticsearch
d) stdout
Answer: b) syslog

22. What does the "stdout" output plugin in Logstash do?

a) Sends data to a standard output (console)
b) Sends data to a database
c) Sends data to a file
d) Sends data to a remote server
Answer: a) Sends data to a standard output (console)

23. Which filter plugin is used to anonymize sensitive data in Logstash?

a) anon
b) anonymize
c) mutate
d) confidential
Answer: b) anonymize

24. How can you run Logstash in debug mode to see detailed log information?

a) --verbose
b) --debug
c) --log-level debug
d) Logstash always runs in debug mode
Answer: b) --debug

25. What is the role of the "clone" filter plugin in Logstash?

a) To create identical copies of log events
b) To split log events into multiple events
c) To merge log events into a single event
d) To filter out specific log events
Answer: a) To create identical copies of log events

26. Which filter plugin is used for encrypting sensitive data in Logstash?

a) cipher
b) encrypt
c) secure
d) anonymize
Answer: a) cipher

27. What is Logstash's role in the ELK Stack architecture?

a) It's responsible for data visualization
b) It's the database component
c) It's responsible for data collection and processing
d) It's the web interface for managing the stack
Answer: c) It's responsible for data collection and processing

28. Which filter plugin is used to parse JSON data in Logstash?

a) json
b) parse_json
c) filter_json
d) json_parser
Answer: a) json

29. In Logstash, what is the role of the "uuid" filter plugin?

a) To generate UUIDs for log events
b) To extract UUIDs from log events
c) To encrypt UUIDs in log events
d) To filter out log events containing UUIDs
Answer: a) To generate UUIDs for log events

30. Which input plugin is used to listen for syslog messages in Logstash?

a) udp
b) tcp
c) syslog
d) input_syslog
Answer: c) syslog

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