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DataStax Cassandra Developer Certification Certification Questions and Answer (Dumps and Practice Questions)



Question : Which of the following is, A Cassandra table-specific, in-memory data structure that resembles a write-back
cache.


: Which of the following is, A Cassandra table-specific, in-memory data structure that resembles a write-back
1. commit log

2. memtable

3. SSTable

4. redo log


Correct Answer : 2
Explanation: A sequentially written commit log on each node captures write activity to ensure data durability.
Data is then indexed and written to an in-memory structure, called a memtable, memtable which resembles a write-back cache





Question : Fill in blanks
Each time the memory structure is full, the data is written to disk in an SSTable data file. All writes are
automatically partitioned and replicated throughout the cluster.
Cassandra periodically consolidates SSTables using a process called __________, discarding obsolete data marked
for deletion with a ___________.
To ensure all data across the cluster stays consistent, various repair mechanisms are employed.
: Fill in blanks
1. compaction, tombstone

2. tombstone, compaction

3. Serialization, compaction

4. repair, compaction

5. tombstone, repair


Correct Answer : 1
Explanation: Cassandra is designed to handle big data workloads across multiple nodes with no
single point of failure. Its architecture is based on the understanding
that system and hardware failures can and do occur. Cassandra addresses the problem of failures by employing a
peer-to-peer distributed system across homogeneous
nodes where data is distributed among all nodes in the cluster. Each node frequently exchanges state information
about itself and other nodes across the cluster
using peer-to-peer gossip communication protocol. A sequentially written commit log on each node captures write
activity to ensure data durability. Data is then indexed
and written to an in-memory structure, called a memtable, memtable which resembles a write-back cache. Each
time the memory structure is full, the data is written to disk
in an SSTable data file. All writes are automatically partitioned and replicated throughout the cluster.
Cassandra periodically consolidates SSTables using a process called
compaction, discarding obsolete data marked for deletion with a tombstone. To ensure all data across the
cluster stays consistent, various repair mechanisms are employed.





Question : What is the meaning of coordinator node.


: What is the meaning of coordinator node.
1. master node in Cassandra cluster.

2. Node which contain master copy of any data.

3. Client read or write requests can be sent to any node in the cluster, and
When a client connects to a node with a request, that node serves as the coordinator for that particular client operation

4. Node which contain configuration for entire cluster.


Correct Answer : 3
Explanation: Cassandra is a partitioned row store database, where rows are organized into tables with
a required primary key. Cassandra's architecture allows any authorized user to
connect to any node in any data center and access data using the CQL language. For ease of use, CQL uses a
similar syntax to SQL and works with table data. Developers can access
CQL through cqlsh, DevCenter, and via drivers for application languages. Typically, a cluster has one KeySpace per
application composed of many different tables.

Client read or write requests can be sent to any node in the cluster. When a client connects to a node
with a request, that node serves as the coordinator for that particular client operation.
The coordinator acts as a proxy between the client application and the nodes that own the data
being requested. The coordinator determines which nodes in the ring should get the request
based on how the cluster is configured.



Related Questions

Question : Which of the following are important components to deciding, on which node a replica needs to be kept.

A. Snitches
B. replication strategy
C. replication factor
D. Partitioner
E. Gossip

 : Which of the following are important components to deciding, on which node a replica needs to be kept.
1. A,B
2. B,C
3. C,D
4. D,E
5. A,E


Question : You have multi-datacenter cluster and a keyspace with, replication factor as . Which of the following will help
you to determine best replica for reading.


 : You have multi-datacenter cluster and a keyspace with, replication factor as . Which of the following will help
1. Snitches

2. replication strategy

3. replication factor

4. Partitioner

5. All replicas are equal and can be read from any node. And no need to find best replica to read.



Question : You must configure a snitch when you create


: You must configure a snitch when you create
1. Keyspace

2. Cluster

3. Table

4. Column Family



Question : Which all of the below can be configured in cassandra.yaml configuration file
A. Caching parameters for tables
B. Properties for tuning and resource utilization
C. Timeout settings
D. Client connections
E. Backups
F. Security

 : Which all of the below can be configured in cassandra.yaml configuration file
1. A,B,C
2. C,D,E
3. D,E,F
4. A,B,E
5. A,B,C,D,E,F


Question : You can set storage configuration attributes on a
A. per-keyspace basis
B. per-table basis
C. per column-family basis
D. per data-center basis

 : You can set storage configuration attributes on a
1. A,B
2. B,C
3. C,D
4. A,D
5. B,D


Question : _______ allows distribution of data across a cluster to minimize reorganization when nodes are added or removed
and it partitions data based on the __________


 : _______ allows distribution of data across a cluster to minimize reorganization when nodes are added or removed
1. Consistent hashing, partition key

2. Random hashing, primary key

3. Consistent hashing, hash key

4. Replication, Replication strategy