DataStax Apache Cassandra Developer Associate Certification — Questions and Answers

Question 1: What role does the CommitLog play in Cassandra's write path?

It merges SSTables during compaction
It provides durability by recording every write before the MemTable (Correct answer)
It indexes partitions for fast lookup
It caches frequently read rows

Correct answer: It provides durability by recording every write before the MemTable

The CommitLog is written to first on every mutation to ensure durability in case of a node crash before the MemTable is flushed.

Question 2: How does increasing the 'memtable_flush_writers' setting improve Cassandra write performance?

It reduces the MemTable size, causing more frequent smaller flushes
It increases the number of threads flushing MemTables to SSTables in parallel, improving throughput on multi-disk setups (Correct answer)
It enables concurrent writes to the same partition
It compresses MemTable data before flushing

Correct answer: It increases the number of threads flushing MemTables to SSTables in parallel, improving throughput on multi-disk setups

More flush writer threads allow Cassandra to flush multiple MemTables to disk concurrently, benefiting systems with multiple data directories or fast SSDs.

Question 3: In cassandra.yaml, what does 'concurrent_reads' control?

The CQL read timeout in milliseconds
The maximum number of SSTables read simultaneously
The number of threads dedicated to serving read requests (Correct answer)
The number of client connections allowed

Correct answer: The number of threads dedicated to serving read requests

concurrent_reads sets the size of the thread pool handling read requests; the default is 32 and can be tuned based on CPU cores and workload.

Question 4: What does the CQL statement 'UPDATE ... IF EXISTS' provide?

A lightweight transaction that only applies the update if the row already exists (Correct answer)
A batch update across multiple partitions
A conditional update using Paxos consensus
An upsert that creates the row if missing

Correct answer: A lightweight transaction that only applies the update if the row already exists

IF EXISTS uses Cassandra's lightweight transaction (LWT) mechanism backed by Paxos to perform a compare-and-swap, only updating if the row already exists.

Question 5: What is the role of 'seed nodes' in a Cassandra cluster?

They store the CommitLog only
They hold the master copy of every partition
They serve as initial contact points for new nodes joining the ring (Correct answer)
They run the schema migration scripts

Correct answer: They serve as initial contact points for new nodes joining the ring

Seed nodes are well-known contact points that new nodes use to learn the cluster topology through the gossip protocol during bootstrap.

Question 6: What is 'key cache' in Cassandra and how does it improve performance?

Caches the most recently executed CQL queries
Caches Bloom filter results to avoid recalculation
Caches the entire row for hot partitions
Caches partition key to SSTable offset mappings, reducing disk seeks for frequently accessed partitions (Correct answer)

Correct answer: Caches partition key to SSTable offset mappings, reducing disk seeks for frequently accessed partitions

The key cache stores the position of a partition key within an SSTable, so Cassandra can skip the index lookup and seek directly to the data on subsequent accesses.

Question 7: Which authorizer must be set in cassandra.yaml to enable GRANT and REVOKE permission management?

PermissionAuthorizer
CassandraAuthorizer (Correct answer)
AllowAllAuthorizer
RoleBasedAuthorizer

Correct answer: CassandraAuthorizer

CassandraAuthorizer stores and enforces permission grants in the system_auth keyspace, enabling fine-grained access control via GRANT and REVOKE statements.

Question 8: Which soft skill is most critical when presenting a Cassandra migration proposal to non-technical stakeholders?

Ability to recite CQL syntax from memory
Demonstrating live nodetool commands
Translating eventual consistency trade-offs into business risk and benefit language (Correct answer)
Explaining the Java heap allocation algorithm in detail

Correct answer: Translating eventual consistency trade-offs into business risk and benefit language

Non-technical stakeholders need business impact framing — uptime, cost, risk — not technical implementation details.

Question 9: Which Cassandra tool is used to inspect ring status, node state, and token distribution from the command line?

cassandra-stress
sstableutil
nodetool (Correct answer)
cqlsh

Correct answer: nodetool

nodetool is the primary administrative CLI for Cassandra, used to view ring status, trigger repairs, flush MemTables, and manage compaction.

Question 10: In Cassandra data modeling, what is 'denormalization'?

Removing duplicate columns from a table
Partitioning a large table into smaller ones
Storing duplicate data in multiple tables to support different query patterns efficiently (Correct answer)
Normalizing data into separate tables with foreign keys

Correct answer: Storing duplicate data in multiple tables to support different query patterns efficiently

Because Cassandra cannot perform joins, data is intentionally duplicated across multiple tables, each designed for a specific query access pattern.

Question 11: What does P in the "CAP" Theorem stand for?

Partition Tolerance (Correct answer)
Partition
Consistency
Availability

Correct answer: Partition Tolerance

In the CAP theorem, P stands for Partition Tolerance — the system keeps operating even when network failures split nodes into groups that can't communicate. The other two properties are Consistency (C) and Availability (A), so 'Availability' and 'Consistency' name different letters, and 'Partition' alone is incomplete since tolerance to partitions is the actual property.

Question 12: What does the Cassandra system keyspace 'system_schema' contain?

Stored CQL prepared statements
Node membership and gossip state
Metadata about all user-defined keyspaces, tables, types, indexes, and views (Correct answer)
Runtime performance metrics for all nodes

Correct answer: Metadata about all user-defined keyspaces, tables, types, indexes, and views

The system_schema keyspace stores the cluster-wide schema metadata including definitions for all keyspaces, tables, columns, UDTs, materialized views, and indexes.

Question 13: Which authenticator must be configured in cassandra.yaml to require clients to provide a username and password?

PasswordAuthenticator (Correct answer)
SecureAuthenticator
CassandraAuthenticator
AllowAllAuthenticator

Correct answer: PasswordAuthenticator

PasswordAuthenticator stores credentials in the system_auth keyspace and requires clients to supply a username and password during connection.

Question 14: What is a 'materialized view' in Cassandra?

A view stored in memory only, not persisted to disk
A read-only cached copy of a base table with a different primary key for alternate access patterns (Correct answer)
A writable denormalized copy of a table managed by the user
A cross-keyspace join of two tables

Correct answer: A read-only cached copy of a base table with a different primary key for alternate access patterns

A materialized view is automatically maintained by Cassandra as a separate table built from a base table, allowing efficient queries on non-primary-key columns.

Question 15: What is the recommended OS setting to change for Cassandra to avoid swap-related performance issues?

Set vm.swappiness=10
Enable zswap with swappiness=100
Set vm.swappiness=0 or 1 (Correct answer)
Disable transparent huge pages and set swappiness=60

Correct answer: Set vm.swappiness=0 or 1

Setting vm.swappiness=1 (or 0) prevents the Linux kernel from swapping Cassandra's JVM heap to disk, which would cause severe latency spikes.

Question 16: What CQL command changes the password for an existing role named 'analyst' in Apache Cassandra?

CHANGE PASSWORD FOR analyst TO 'newpass'
UPDATE ROLE analyst WITH PASSWORD = 'newpass'
ALTER ROLE analyst WITH PASSWORD = 'newpass' (Correct answer)
SET PASSWORD FOR analyst = 'newpass'

Correct answer: ALTER ROLE analyst WITH PASSWORD = 'newpass'

ALTER ROLE is the correct CQL command to modify role properties including password, login capability, and superuser status.

Question 17: What is the purpose of a Bloom filter in Cassandra?

Merge overlapping SSTables
Compress SSTables on disk
Enforce row-level security
Quickly determine if an SSTable may contain a given partition key (Correct answer)

Correct answer: Quickly determine if an SSTable may contain a given partition key

A Bloom filter is a probabilistic data structure that lets Cassandra skip reading SSTables that definitely do not contain the requested key.

Question 18: What is the impact of too many tombstones in a Cassandra partition?

Increased write throughput
Degraded read performance because Cassandra must scan and filter tombstones during reads (Correct answer)
Faster compaction cycles
Reduced replication overhead

Correct answer: Degraded read performance because Cassandra must scan and filter tombstones during reads

Reads must traverse tombstones to determine what data is live; a partition with millions of tombstones can cause read timeouts and TombstoneOverwhelmingException.

Question 19: What tool can be used to run benchmark load tests against a Cassandra cluster?

cassandra-stress (Correct answer)
cqlsh --bench
sstableloader --test
nodetool benchmark

Correct answer: cassandra-stress

cassandra-stress is a built-in benchmarking tool that generates configurable read/write workloads to measure cluster throughput and latency.

Question 20: What does the term 'eventual consistency' mean in the context of Cassandra?

All replicas will converge to the same value given no new updates (Correct answer)
Reads always return the latest write
Writes are synchronous across all replicas
All nodes are always in sync

Correct answer: All replicas will converge to the same value given no new updates

Eventual consistency guarantees that if no new updates are made, all replicas will eventually return the same value.

Question 21: What does the 'listen_address' parameter in cassandra.yaml define?

The address of the seed node
The Thrift RPC address
The IP address the node uses to communicate with other nodes in the cluster (Correct answer)
The address Cassandra listens on for CQL client connections

Correct answer: The IP address the node uses to communicate with other nodes in the cluster

listen_address is the IP that other Cassandra nodes use to reach this node for inter-node communication (gossip, streaming, repairs).

Question 22: When should you use a Cassandra Materialized View instead of a denormalized table?

When you need Cassandra to automatically maintain a read-optimized copy of a base table (Correct answer)
When you want to reduce storage usage by sharing rows across tables
When write throughput must exceed 1 million ops/sec
When consistency level ONE is required for all reads

Correct answer: When you need Cassandra to automatically maintain a read-optimized copy of a base table

Materialized Views are automatically updated by Cassandra when the base table changes, eliminating the need for application-level dual writes.

Question 23: What does the 'nodetool snapshot' command create?

A dump of all keyspace schemas to a SQL file
An incremental backup delta file
A full backup by hard-linking current SSTable files into a snapshot directory (Correct answer)
A binary export of the CommitLog

Correct answer: A full backup by hard-linking current SSTable files into a snapshot directory

nodetool snapshot creates a point-in-time backup by hard-linking the current SSTable files into a per-keyspace snapshot directory without copying data.

Question 24: Which architecture model does Apache Cassandra follow?

Primary-secondary with arbiter
Hub-and-spoke
Master-slave
Peer-to-peer (masterless) (Correct answer)

Correct answer: Peer-to-peer (masterless)

Cassandra uses a fully peer-to-peer masterless architecture where every node can accept reads and writes.

Question 25: What is the 'replication factor' in a Cassandra keyspace?

The compression ratio of SSTables
The number of copies of each partition stored across the cluster (Correct answer)
The consistency level for reads
The number of nodes in the cluster

Correct answer: The number of copies of each partition stored across the cluster

The replication factor defines how many nodes store a replica of each partition, directly affecting fault tolerance.

Question 26: A developer wants to transition from a relational DBA role to a Cassandra DBA. What is the most important mindset shift required?

Replacing transactions with eventual consistency and query-first design (Correct answer)
Adopting row-level locking for concurrency control
Prioritizing referential integrity constraints
Learning to write more complex stored procedures

Correct answer: Replacing transactions with eventual consistency and query-first design

The biggest shift is embracing eventual consistency and designing schemas around queries rather than data relationships.

Question 27: Which value of the 'internode_encryption' setting in server_encryption_options encrypts only traffic between datacenters while leaving intra-datacenter traffic unencrypted?

none
rack
dc (Correct answer)
all

Correct answer: dc

Setting internode_encryption to 'dc' encrypts inter-datacenter gossip and streaming while leaving same-datacenter node communications unencrypted, balancing security and performance.

Question 28: What is the difference between a partition key and a clustering key in a Cassandra primary key?

The partition key is optional; the clustering key is mandatory
The clustering key determines which node stores data; the partition key sorts rows
There is no difference; they are synonyms
The partition key determines data distribution; clustering keys determine sort order within a partition (Correct answer)

Correct answer: The partition key determines data distribution; clustering keys determine sort order within a partition

The partition key routes data to a node via consistent hashing, while clustering columns control the physical sort order of rows stored within that partition.

Question 29: What mechanism does Cassandra use to detect and recover from failed nodes automatically?

Raft leader election
Paxos consensus
Gossip protocol with hinted handoff (Correct answer)
ZooKeeper coordination

Correct answer: Gossip protocol with hinted handoff

Cassandra uses gossip for failure detection and hinted handoff to store missed writes temporarily on behalf of a down replica.

Question 30: Only columns with a __ that are not the primary key can use the where clause.

Sparse Index
Primary Index
Secondary Index (Correct answer)
Dense Index

Correct answer: Secondary Index

Explanation: <br> In Cassandra, the WHERE clause can be used to filter the data based on certain conditions. When querying data, the WHERE clause can be applied to any column in the table, whether it is a primary key or a non-key column. However, when querying a table based on a non-key column, an index is required to be created on that column.

Question 31: What is the purpose of 'gc_grace_seconds' in Cassandra?

The delay before a MemTable flush
The grace period for schema change propagation
The period tombstones must persist before being eligible for deletion during compaction (Correct answer)
The time before a node is evicted from the ring

Correct answer: The period tombstones must persist before being eligible for deletion during compaction

gc_grace_seconds ensures tombstones are not removed before all replicas have had a chance to propagate the deletion, preventing deleted data from re-appearing.

Question 32: What is 'read repair' in Apache Cassandra?

Synchronizing divergent replicas by comparing and updating them during a read (Correct answer)
Rewriting outdated partition keys
Compacting SSTables after a read-heavy period
Rebuilding corrupt SSTables

Correct answer: Synchronizing divergent replicas by comparing and updating them during a read

Read repair detects inconsistencies between replicas during a read operation and writes the most recent data back to out-of-date replicas.

Question 33: What does a Cassandra consistency level of QUORUM mean for a cluster with a replication factor of 3?

Only 1 replica must acknowledge
The nearest replica must acknowledge
All 3 replicas must acknowledge
At least 2 replicas must acknowledge (Correct answer)

Correct answer: At least 2 replicas must acknowledge

QUORUM requires a majority, calculated as floor(RF/2) + 1, so for RF=3 that means 2 acknowledgments.

Question 34: Which professional organization or community should a Cassandra engineer join for peer networking in the US?

The Oracle User Group (IOUG) exclusively
IBM DB2 user groups only
Microsoft SQL Server PASS community
The Apache Cassandra community Slack and local NoSQL meetups (Correct answer)

Correct answer: The Apache Cassandra community Slack and local NoSQL meetups

The official Apache Cassandra Slack community and local NoSQL/data engineering meetups are the most relevant peer networks.

Question 35: What does 'speculative execution' do in Cassandra drivers?

Pre-compiles CQL statements to reduce parse overhead
Sends duplicate requests to multiple replicas and uses the fastest response to reduce tail latency (Correct answer)
Pre-fetches the next page of results
Executes a query on a secondary index speculatively

Correct answer: Sends duplicate requests to multiple replicas and uses the fastest response to reduce tail latency

Speculative execution fires off the same query to an additional replica after a configurable delay, reducing tail latency by using the faster response.

Question 36: What is a user-defined type (UDT) in Cassandra CQL?

A custom partition key type
A custom compaction strategy
A named group of typed fields that can be embedded as a column value in a table (Correct answer)
A stored procedure written in Java

Correct answer: A named group of typed fields that can be embedded as a column value in a table

A UDT allows you to define a reusable composite type with named fields (e.g., address with street, city, zip) that can be used as a column value in tables.

Question 37: What does 'nodetool compact' do?

Rebalances token ranges across nodes
Triggers a major compaction of all SSTables for a keyspace/table into a single SSTable (Correct answer)
Flushes all MemTables to disk
Deletes expired tombstones immediately

Correct answer: Triggers a major compaction of all SSTables for a keyspace/table into a single SSTable

nodetool compact merges all SSTables for the specified table into one, removing tombstones and reducing read amplification at the cost of high temporary disk usage.

Question 38: What are the default superuser credentials in a freshly installed Apache Cassandra cluster?

user / password
cassandra / cassandra (Correct answer)
admin / admin
root / cassandra

Correct answer: cassandra / cassandra

Cassandra ships with a default superuser account where both the username and password are 'cassandra', which must be changed immediately in production.

Question 39: Which conference is most closely associated with the Apache Cassandra community for professional networking?

AWS re:Invent (database track only)
Cassandra Summit / DataStax Accelerate (Correct answer)
OracleWorld
MongoDB .local

Correct answer: Cassandra Summit / DataStax Accelerate

Cassandra Summit (rebranded as DataStax Accelerate) is the primary conference dedicated to the Cassandra ecosystem.

Question 40: What is 'write amplification' in the context of Cassandra compaction?

The number of replicas a write is sent to
The overhead of writing both MemTable and CommitLog
The ratio of reads to writes during compaction
The multiple of data written to disk relative to the actual data inserted due to compaction rewriting SSTables (Correct answer)

Correct answer: The multiple of data written to disk relative to the actual data inserted due to compaction rewriting SSTables

Write amplification occurs because compaction must read and rewrite SSTables to merge them, causing significantly more disk I/O than the original writes.

Question 41: How can you monitor the number of pending compaction tasks on a Cassandra node in real time?

nodetool compactionstats (Correct answer)
SELECT * FROM system.compactions
nodetool cfstats | grep pending
cqlsh -e 'SHOW COMPACTIONS'

Correct answer: nodetool compactionstats

`nodetool compactionstats` displays currently running and pending compaction tasks along with their progress and estimated completion.

Question 42: Which Cassandra feature allows you to set an automatic expiration time on individual rows or columns?

Materialized views
Lightweight transactions (LWT)
Compaction strategy
TTL (Time To Live) (Correct answer)

Correct answer: TTL (Time To Live)

TTL sets a time-to-live in seconds on data, after which Cassandra marks it with a tombstone and eventually removes it.

Question 43: Which Cassandra knowledge area is increasingly important as teams adopt cloud-native deployments on Kubernetes?

Writing Oracle PL/SQL stored procedures
Managing physical server RAID arrays manually
Configuring on-premises SAN storage arrays
Operating Cassandra with K8ssandra or Cass-operator on Kubernetes (Correct answer)

Correct answer: Operating Cassandra with K8ssandra or Cass-operator on Kubernetes

K8ssandra and the Cass-operator project bring Cassandra-specific operational knowledge to Kubernetes, making this a growing skill area.

Question 44: What CQL command is used to examine the current schema of a table, including its primary key and options?

DESCRIBE TABLE tablename (Correct answer)
EXPLAIN TABLE tablename
SHOW CREATE TABLE tablename
SELECT * FROM schema_tables WHERE name='tablename'

Correct answer: DESCRIBE TABLE tablename

In cqlsh, DESCRIBE TABLE (or DESC TABLE) outputs the full CREATE TABLE statement for the specified table including all columns, types, and table properties.

Question 45: What is 'anti-entropy repair' in Cassandra?

A process that rebuilds Bloom filters for all SSTables
A repair mechanism that uses Merkle tree comparisons to identify and fix replica inconsistencies (Correct answer)
A compaction process that removes duplicate cells
A background process that validates CommitLog checksums

Correct answer: A repair mechanism that uses Merkle tree comparisons to identify and fix replica inconsistencies

Anti-entropy repair builds Merkle trees of partition data on each replica, compares them to find diverging ranges, and streams the correct data to out-of-sync replicas.

Question 46: Which JVM garbage collector is recommended for Cassandra to minimize GC pause times?

Parallel GC
Serial GC
G1GC or ZGC (Correct answer)
CMS GC

Correct answer: G1GC or ZGC

G1GC (and increasingly ZGC for newer JDKs) is recommended for Cassandra to keep GC pauses short and avoid stop-the-world events that affect latency.

Question 47: What is 'tombstone' in Cassandra?

A marker written at node startup
A deletion marker stored in SSTables to represent deleted data (Correct answer)
A backup snapshot file
A log entry for schema changes

Correct answer: A deletion marker stored in SSTables to represent deleted data

A tombstone is a deletion marker written to an SSTable that tells Cassandra to ignore older versions of that data during reads.

Question 48: Which nodetool command triggers a full repair to synchronize data across all replicas for a keyspace?

nodetool compaction
nodetool cleanup
nodetool sync
nodetool repair (Correct answer)

Correct answer: nodetool repair

`nodetool repair` performs anti-entropy repair, comparing Merkle trees across replicas and streaming any missing or divergent data.

Question 49: Which configuration file is the primary settings file for a Cassandra node?

logback.xml
cassandra.yaml (Correct answer)
jvm.options
cassandra-env.sh

Correct answer: cassandra.yaml

cassandra.yaml contains the core node configuration including cluster name, data directories, seeds, listen address, and replication settings.

Question 50: Which compaction strategy is best suited for time-series data that is mostly appended and rarely updated?

UnifiedCompactionStrategy (UCS)
SizeTieredCompactionStrategy (STCS)
LeveledCompactionStrategy (LCS)
TimeWindowCompactionStrategy (TWCS) (Correct answer)

Correct answer: TimeWindowCompactionStrategy (TWCS)

TWCS groups SSTables into time windows and compacts within each window, making it ideal for time-series data with little or no overwrites.

Question 51: When did Cassandra first become available?

July 2007
July 2005
July 2006
July 2008 (Correct answer)

Correct answer: July 2008

Explanation: <br> Cassandra was first created on Facebook by Prashant Malik and Avinash Lakshman, one of the inventors of Amazon's Dynamo, to support the Facebook inbox search feature. In July 2008, Facebook published Cassandra as an open-source project on Google Code. It was accepted as an Apache Incubator project in March 2009. The project advanced to a top-level project on February 17, 2010. <br> <br> With historical references to a curse on an oracle, Facebook's database was given the name Cassandra by its creators in honour of the Trojan fabled prophet.

Question 52: Which Cassandra operational task should be automated first when a professional joins a new team to reduce toil?

Restarting all seed nodes on a weekly schedule
Manually triggering compaction on every node during business hours
Manually reading all cassandra.yaml files line by line each day
Automating nodetool repair scheduling with a tool like Reaper to prevent data inconsistency accumulation (Correct answer)

Correct answer: Automating nodetool repair scheduling with a tool like Reaper to prevent data inconsistency accumulation

Cassandra Reaper automates anti-entropy repair scheduling, which is the most operationally critical and time-consuming manual task.

Question 53: Which of the following best describes the role of the snitch in Apache Cassandra?

Informs Cassandra about network topology so replicas are placed in different racks or datacenters (Correct answer)
Monitors gossip traffic and removes nodes that fail to heartbeat
Detects and removes corrupt SSTables from the data directory
Coordinates lightweight transactions by acting as the Paxos proposer

Correct answer: Informs Cassandra about network topology so replicas are placed in different racks or datacenters

The snitch tells Cassandra about the relative network proximity of nodes, enabling intelligent replica placement across racks and datacenters.

Question 54: What consistency level in Cassandra offers the lowest latency but the weakest consistency guarantee?

QUORUM
ALL
ONE (Correct answer)
LOCAL_QUORUM

Correct answer: ONE

Consistency level ONE requires only a single replica to respond, giving the lowest latency but risking stale reads if another replica has a newer version.

Question 55: What is the primary data distribution mechanism in Apache Cassandra?

Round-robin assignment
Master-slave replication
Sharding by row key prefix
Consistent hashing with a token ring (Correct answer)

Correct answer: Consistent hashing with a token ring

Cassandra uses consistent hashing on a token ring to distribute data evenly across nodes without a central coordinator.

Question 56: What does 'vnodes' (virtual nodes) provide in Cassandra?

More even data distribution by assigning multiple token ranges per physical node (Correct answer)
Virtual replicas for read performance
Logical shards for multi-tenancy
Isolated namespaces for keyspaces

Correct answer: More even data distribution by assigning multiple token ranges per physical node

Vnodes assign multiple non-contiguous token ranges to each physical node, resulting in more balanced data distribution and easier cluster scaling.

Question 57: What is a 'token-aware' load balancing policy in a Cassandra driver, and why is it preferred?

It balances load by always sending writes to the node with the fewest open connections
It forces reads through the coordinator to ensure consistency level compliance
It routes requests to the node that owns the relevant partition, reducing hops (Correct answer)
It distributes requests round-robin among all nodes regardless of token ownership

Correct answer: It routes requests to the node that owns the relevant partition, reducing hops

Token-aware routing sends queries directly to the replica that owns the data, avoiding an extra coordinator hop and reducing latency.

Question 58: What does the 'nodetool cfstats' (or 'tablestats') command report?

Cross-node cluster topology statistics
CommitLog segment usage per table
Network bandwidth consumed per table
Column family (table) level statistics including read/write latency, SSTable count, partition size, and tombstone metrics (Correct answer)

Correct answer: Column family (table) level statistics including read/write latency, SSTable count, partition size, and tombstone metrics

nodetool tablestats provides per-table metrics such as mean partition size, SSTable count, read/write counts, and tombstone warnings, critical for diagnosing table-level issues.

Question 59: What is the default native transport port used by Cassandra for CQL client connections?

7199
7001
7000
9042 (Correct answer)

Correct answer: 9042

Port 9042 is the default CQL native transport port that drivers and tools like cqlsh use to connect to Cassandra.

Question 60: What is the recommended strategy for the system_auth keyspace replication in a multi-datacenter production cluster?

SimpleStrategy with RF=3 globally
SimpleStrategy with RF=1 (default)
NetworkTopologyStrategy with RF matching the number of nodes in each DC (Correct answer)
NetworkTopologyStrategy with RF=1 per DC

Correct answer: NetworkTopologyStrategy with RF matching the number of nodes in each DC

Using NetworkTopologyStrategy with a replication factor matching each datacenter's node count ensures authentication data is available even during node failures across all DCs.

DataStax Apache Cassandra Developer Associate Certification

The DataStax Apache Cassandra Developer Associate certification validates knowledge of CQL, data modeling, Cassandra architecture, and cluster operations. It targets developers and administrators working with Apache Cassandra in production environments.

Questions

45 min

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70%

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