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

Correct Answer : 1
Explanation: A snitch defines groups of machines into data centers and racks (the topology) that the replication
strategy uses to place replicas.
A snitch determines which data centers and racks nodes belong to. They inform Cassandra about the network topology so that
requests are routed efficiently
and allows Cassandra to distribute replicas by grouping machines into data centers and racks. Specifically, the replication
strategy places the replicas based on the
information provided by the new snitch. All nodes must return to the same rack and data center. Cassandra does its best not to
have more than one replica





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.


Correct Answer : 1
Explanation: All snitches use a dynamic snitch layer, which monitors performance and chooses the best replica for
reading.
It is enabled by default and recommended for use in most deployments. Configure dynamic snitch thresholds for each node in the
cassandra.yaml configuration file.

The default SimpleSnitch does not recognize data center or rack information. Use it for single-data center deployments or
single-zone in public clouds.
The GossipingPropertyFileSnitch is recommended for production. It defines a node's data center and rack and uses gossip for
propagating this information to other nodes.





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


Correct Answer : 2
Explanation: A snitch defines groups of machines into data centers and racks (the topology) that the replication
strategy uses to place replicas.

You must configure a snitch when you create a cluster. All snitches use a dynamic snitch layer, which monitors performance and
chooses the best replica for reading.
It is enabled by default and recommended for use in most deployments. Configure dynamic snitch thresholds for each node in the
cassandra.yaml configuration file.

The default SimpleSnitch does not recognize data center or rack information. Use it for single-data center deployments or
single-zone in public clouds.
The GossipingPropertyFileSnitch is recommended for production. It defines a node's data center and rack and uses gossip for
propagating this information to other nodes.



Related Questions

Question : . If you have a multi-data center cluster setup, than include at least one node from each datacenter (replication
group) in the seed list.
 : . If you have a multi-data center cluster setup, than include at least one node from each datacenter (replication
1. True
2. False


Question : Please map the following

A. Dynamic snitching
B. RackInferringSnitch
C. GossipingPropertyFileSnitch

1. Monitors the performance of reads from the various replicas and chooses the best replica based on this history.
2. Determines the location of nodes by rack and datacenter corresponding to the IP addresses.
3. Automatically updates all nodes using gossip when adding new nodes and is recommended for production.

 : Please map the following
1. A-3, B-1, C-3
2. A-3, B-2, C-1
3. A-1, B-2, C-3
4. A-1, B-3, C-2


Question : When you set replication factor as , it means total copy of same data will be created
 : When you set replication factor as , it means total copy of same data will be created
1. True
2. False


Question : You have been given below ER Diagram

What is the correct table design to satisfy below query?

Query: Find all author that matches specific category and also show the most recently published first
 : You have been given below ER Diagram
1. A
2. B
3. C
4. D


Question : Which one would you prefer , when data duplication is done because of schema design ?

 : Which one would you prefer , when data duplication is done because of schema design ?
1. Constant duplication

2. Exponential duplication

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4. 1 and 2

4. 1 and 3



Question : You have been given below ER Diagram

What is the correct table design to satisfy below query?

Query: Find all books that is subscribed by a subscriber and support writing year range, with most writing year first then
sorted by title.

 : You have been given below ER Diagram
1. A
2. B
 3. Access Mostly Uused Products by 50000+ Subscribers
4. D