ElasticSearch ElasticSearch Cluster Management & Administration 2 — Questions and Answers
Question 1: Which node role in Elasticsearch is responsible for hosting document data and executing data-related operations like search and CRUD?
- master
- ingest
- data (Correct answer)
- coordinating
Correct answer: data
The 'data' node role is responsible for storing indexed documents and performing operations such as search, aggregation, and CRUD requests.
Question 2: What did the discovery.zen.minimum_master_nodes setting control in Elasticsearch versions prior to 7.0?
- The maximum number of master nodes allowed
- The quorum of votes needed to elect a master and prevent split-brain (Correct answer)
- Which nodes are eligible to become master
- The number of voting-only nodes in the cluster
Correct answer: The quorum of votes needed to elect a master and prevent split-brain
discovery.zen.minimum_master_nodes defined the quorum (typically (N/2)+1) required to elect a master, preventing two partitions from each electing their own master.
Question 3: What does the node.roles configuration setting define in Elasticsearch 7.9 and later?
- Lists all currently active nodes in the cluster
- Defines the functional roles assigned to a specific node (Correct answer)
- Sets the maximum number of roles permitted per cluster
- Configures role-based access control for API endpoints
Correct answer: Defines the functional roles assigned to a specific node
node.roles allows explicit assignment of roles (master, data, ingest, ml, etc.) to a node, replacing older boolean role settings like node.master and node.data.
Question 4: Which API is used to update cluster-wide settings dynamically without restarting any Elasticsearch nodes?
- PUT /_cluster/settings (Correct answer)
- POST /_nodes/reload_secure_settings
- PUT /_cluster/reroute
- POST /_cluster/update
Correct answer: PUT /_cluster/settings
The PUT /_cluster/settings API allows updating persistent and transient cluster settings at runtime without requiring a node or cluster restart.
Question 5: What is the key difference between 'persistent' and 'transient' settings in the Elasticsearch cluster settings API?
- Persistent settings apply to all nodes; transient settings apply only to the master
- Persistent settings survive full cluster restarts; transient settings are lost on full cluster restart (Correct answer)
- Persistent settings are read-only; transient settings can be changed at any time
- Persistent settings require a node restart; transient settings take effect immediately
Correct answer: Persistent settings survive full cluster restarts; transient settings are lost on full cluster restart
Persistent settings are written to the cluster state and survive full cluster restarts, while transient settings are cleared when the entire cluster restarts.
Question 6: What is the primary function of an 'ingest' node in Elasticsearch?
- Coordinating bulk indexing requests across data nodes
- Pre-processing documents through ingest pipelines before indexing (Correct answer)
- Ingesting data streams directly from external sources like Kafka
- Managing the cluster's overall indexing throughput capacity
Correct answer: Pre-processing documents through ingest pipelines before indexing
Ingest nodes run ingest pipelines that transform documents — using processors like grok, set, and rename — before the documents are passed to data nodes for indexing.
Question 7: What role do coordinating-only nodes play in an Elasticsearch cluster?
- They route requests, merge results, and handle scatter-gather without storing data (Correct answer)
- They coordinate master election between master-eligible nodes
- They store coordination metadata for the cluster state
- They manage cross-cluster replication coordination between clusters
Correct answer: They route requests, merge results, and handle scatter-gather without storing data
Coordinating-only nodes act as intelligent load balancers — they route requests to the appropriate shards, collect partial results, and merge them without holding data or master responsibilities.
ElasticSearch ElasticSearch Cluster Management & Administration 2
Which node role in Elasticsearch is responsible for hosting document data and executing data-related operations like search and CRUD?