CASSANDRA Cheat Sheet 2026

The 30 highest-yield CASSANDRA facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the effect of setting 'WITH LOGIN = false' when creating or altering a Cassandra role? → The role cannot be used to open a client connection to Cassandra
2. Which Cassandra metric indicates that a node is receiving more writes than it can process? → High MutationStage pending tasks in tpstats
3. What is the 'sstableloader' tool used for in Cassandra? → Bulk-loading existing SSTable files into a running Cassandra cluster
4. What is the purpose of 'incremental_backups' in Cassandra? → Copies each new SSTable to a backups/ subdirectory after it is flushed from MemTable
5. What role does the CommitLog play in Cassandra's write path? → It provides durability by recording every write before the MemTable
6. What Cassandra version do you use? → 3.9
7. What availability risk is introduced by leaving the system_auth keyspace at its default replication factor of 1? → A single node failure can make authentication unavailable cluster-wide
8. What does the 'nodetool snapshot' command create? → A full backup by hard-linking current SSTable files into a snapshot directory
9. What is the primary data distribution mechanism in Apache Cassandra? → Consistent hashing with a token ring
10. Cassandra was created by who? → Facebook
11. Which tool is employed to view a table's statistics? → Nodetool
12. In Cassandra data modeling, what is 'denormalization'? → Storing duplicate data in multiple tables to support different query patterns efficiently
13. What is a user-defined type (UDT) in Cassandra CQL? → A named group of typed fields that can be embedded as a column value in a table
14. What is the purpose of 'gc_grace_seconds' in Cassandra? → The period tombstones must persist before being eligible for deletion during compaction
15. What is the purpose of a secondary index in Cassandra? → To allow queries on non-primary-key columns without needing ALLOW FILTERING
16. By "Table in Cassandra," what do you mean? → Column-Family
17. What does the 'endpoint_snitch' configuration control in Cassandra? → How Cassandra determines the topology (rack/DC) of nodes for replica placement
18. How do you safely perform a rolling upgrade of a Cassandra cluster? → Upgrade and restart one node at a time, verifying stability before proceeding to the next
19. What is an SSTable in Apache Cassandra? → An immutable on-disk file that stores sorted partition data
20. How do you enable authentication in Cassandra? → Set authenticator: PasswordAuthenticator in cassandra.yaml
21. What CQL command is used to examine the current schema of a table, including its primary key and options? → DESCRIBE TABLE tablename
22. Which permission keyword in Cassandra grants all available privileges on a given resource? → ALL
23. What does 'hinted handoff' do when a replica node is temporarily down? → The coordinator stores the write as a hint and replays it to the node when it recovers
24. What CQL statement is used to create a new keyspace in Cassandra? → CREATE KEYSPACE
25. Which component in Cassandra is responsible for in-memory writes before they are flushed to disk? → MemTable
26. What is the 'replication factor' in a Cassandra keyspace? → The number of copies of each partition stored across the cluster
27. What is the recommended strategy for the system_auth keyspace replication in a multi-datacenter production cluster? → NetworkTopologyStrategy with RF matching the number of nodes in each DC
28. What does 'nodetool repair' do in Cassandra? → Synchronizes replicas by comparing and streaming missing data between nodes
29. Which cassandra.yaml configuration section enables SSL/TLS encryption for internode (node-to-node) communication within a Cassandra cluster? → server_encryption_options
30. What is Cassandra a mix of? → Bigtable + dynamo