ElasticSearch Technology & Digital Applications 3 — Questions and Answers
Question 1: What is the purpose of Elasticsearch's 'index templates'?
- To create visual dashboards for index data
- To automatically apply settings and mappings to new indices (Correct answer)
- To replicate indices to another cluster
- To define access control policies per index
Correct answer: To automatically apply settings and mappings to new indices
Index templates define settings, mappings, and aliases that are automatically applied when a new index matching a specified pattern is created.
Question 2: Which aggregation type in Elasticsearch would you use to calculate the average value of a numeric field?
- Terms aggregation
- Histogram aggregation
- Avg metric aggregation (Correct answer)
- Cardinality aggregation
Correct answer: Avg metric aggregation
The avg metric aggregation computes the average of numeric values extracted from documents in the aggregation scope.
Question 3: What does ILM stand for in the context of Elasticsearch?
- Index Lifecycle Management (Correct answer)
- Integrated Log Monitoring
- Index Level Mapping
- Internal Load Management
Correct answer: Index Lifecycle Management
ILM (Index Lifecycle Management) automates the management of indices over time, moving them through hot, warm, cold, and delete phases.
Question 4: In Elasticsearch, what is a 'bucket' aggregation?
- An aggregation that computes a single metric value
- An aggregation that groups documents into buckets based on criteria (Correct answer)
- A type of filter that limits query scope
- A storage container for large binary documents
Correct answer: An aggregation that groups documents into buckets based on criteria
Bucket aggregations group documents into buckets based on field values, ranges, or other criteria, allowing further sub-aggregations within each bucket.
Question 5: What does the Elasticsearch 'explain' API parameter do?
- Returns the query parse tree
- Shows why a document matched or didn't match and its relevance score (Correct answer)
- Lists all indices matching a pattern
- Describes the cluster health status
Correct answer: Shows why a document matched or didn't match and its relevance score
The explain parameter returns detailed information about how the relevance score was computed for each matching document.
Question 6: Which Elasticsearch feature enables real-time alerting based on query results?
- Snapshot lifecycle policies
- Watchers (Elasticsearch Alerting) (Correct answer)
- Cross-cluster replication
- Field data cache
Correct answer: Watchers (Elasticsearch Alerting)
Elasticsearch Watcher (part of X-Pack) monitors data and sends alerts based on conditions evaluated against scheduled query results.
Question 7: What is the role of the 'coordinating node' in an Elasticsearch cluster?
- It stores all index data permanently
- It routes requests, merges results, and coordinates distributed operations (Correct answer)
- It manages cluster state and master election
- It performs segment merges during low traffic
Correct answer: It routes requests, merges results, and coordinates distributed operations
Coordinating nodes receive client requests, forward them to the appropriate shards, collect results, and return the final merged response to the client.
ElasticSearch Technology & Digital Applications 3
What is the purpose of Elasticsearch's 'index templates'?