Elastic

• What is the Elastic Stack?
• Explain what is Elasticsearch
• What is Logstash?
• Explain what beats are
• What is Kibana?
• Describe what happens from the moment an app logged some information until it’s displayed to the user in a dashboard when the Elastic stack is used

Elasticsearch

• What is a data node?
• What is a master node?
• What is an ingest node?
• What is Coordinating node?
• How data is stored in elasticsearch?
• What is an Index?
• Explain Shards
• What is an Inverted Index?
• What is a Document?
• You check the health of your elasticsearch cluster and it’s red. What does it mean? What can cause the status to be yellow instead of green?
• True or False? Elasticsearch indexes all data in every field and each indexed field has the same data structure for unified and quick query – ability
• What reserved fields a document has?
• Explain Mapping
• What are the advantages of defining your own mapping? (or: when would you use your own mapping?)
• Explain Replicas
• Can you explain Term Frequency & Document Frequency?
• You check “Current Phase” under “Index lifecycle management” and you see it’s set to “hot”. What does it mean?
• What this command does? curl -X PUT “localhost:9200/customer/_doc/1?pretty” -H ‘Content-Type: application/json’ -d'{ “name”: “John Doe” }’
• What will happen if you run the previous command twice? What about running it 100 times?
• What is the Bulk API? What would you use it for?
• Query DSL
• Explain Elasticsearch query syntax (Booleans, Fields, Ranges)
• Explain what is Relevance Score
• Explain Query Context and Filter Context
• Describe how would an architecture of production environment with large amounts of data would be different from a small-scale environment

Logstash

• What are Logstash plugins? What plugins types are there?
  What is grok?
• How grok works?
• What grok patterns are you familiar with?
• What is _grokparsefailure?
• How do you test or debug grok patterns?
• What are Logstash Codecs? What codecs are there?

Kibana

• What can you find under “Discover” in Kibana?
• You see in Kibana, after clicking on Discover, “561 hits”. What does it mean?
• What can you find under “Visualize”?
• What visualization types are supported/included in Kibana?
• What visualization type would you use for statistical outliers
• Describe in detail how do you create a dashboard in Kibana

Filebeat

• What is Filebeat?
• If one is using ELK, is it a must to also use filebeat? In what scenarios it’s useful to use filebeat?-
• What is a harvester?
• True or False? a single harvester harvest multiple files, according to the limits set in filebeat.yml
• What are filebeat modules?

Elastic Stack

• How do you secure an Elastic Stack?

Rajesh Kumar

I’m a DevOps/SRE/DevSecOps/Cloud Expert passionate about sharing knowledge and experiences. I am working at Cotocus. I blog tech insights at DevOps School, travel stories at Holiday Landmark, stock market tips at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at I reviewed , and SEO strategies at Wizbrand. 

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