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

1. True
2. False

Correct Answer : Get Lastest Questions and Answer :
Explanation: : In multiple data-center clusters, include at least one node from each datacenter (replication
group) in the seed list. Designating more than a single seed node per datacenter is recommended for fault tolerance.
Otherwise, gossip has to communicate with another datacenter when bootstrapping a node.
Making every node a seed node is not recommended because of increased maintenance and reduced gossip performance. Gossip
optimization is not critical, but it is recommended to use a small seed list (approximately three nodes per datacenter).

Gossip information is also persisted locally by each node to use immediately when a node restarts.





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.


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

Correct Answer : Get Lastest Questions and Answer :
Explanation: Dynamic snitching: Monitors the performance of reads from the various replicas and chooses the best
replica based on this history.
SimpleSnitch : The SimpleSnitch is used only for single-datacenter deployments.
RackInferringSnitch : Determines the location of nodes by rack and datacenter corresponding to the IP addresses.
PropertyFileSnitch : Determines the location of nodes by rack and datacenter.
GossipingPropertyFileSnitch : Automatically updates all nodes using gossip when adding new nodes and is recommended for
production.
Ec2Snitch : Use the Ec2Snitch with Amazon EC2 in a single region.
Ec2MultiRegionSnitch : Use the Ec2MultiRegionSnitch for deployments on Amazon EC2 where the cluster spans multiple regions.
GoogleCloudSnitch : Use the GoogleCloudSnitch for Cassandra deployments on Google Cloud Platform across one or more regions.
CloudstackSnitch : Use the CloudstackSnitch for Apache Cloudstack environments.





Question : When you set replication factor as , it means total copy of same data will be created

1. True
2. False

Correct Answer : Get Lastest Questions and Answer :
Explanation: No of Data copy = Replication factor.

Related Questions

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Question : When multiple occurrences of data match a condition in a WHERE clause, Cassandra selects the most-frequent
occurrence of a condition for processing first for efficiency.



1. True
2. False


Question : You have been given two separate csv file as below.

course.csv : with following sample data

62c36092-82a1-3a00-93d1-46196ee77204, cassandra,{nosql,bigdata},

subscriber.csv (All the subscriber of the training course, it is possible a single company can have multiple user)
62c36092-82a1-3a00-93d1-46196ee77204, {hadoopexam@gmail.com, admin@hadoopexam.com} , Amit Jain

Which of the following is correct way to accommodate these data in Cassandra table?

A.
CREATE TABLE HADOOPEXAM {
course_id timeuuid,
title text,
Category set
}

CREATE TYPE SUBSCRIBER_TYPE {
course_id timeuuid,
emails set,
name text
}

ALTER TABLE HADOOPEXAM add SUBSCRIBER frozen;

B.

CREATE TYPE SUBSCRIBER_TYPE {
course_id timeuuid,
emails set,
name text
}

CREATE TABLE HADOOPEXAM {
course_id timeuuid,
title text,
Category set,
SUBSCRIBER SUBSCRIBER_TYPE
}

C.
CREATE TABLE SUBSCRIBER_TYPE {
course_id timeuuid,
emails set,
name text
}

CREATE TABLE HADOOPEXAM {
course_id timeuuid,
title text,
Category set,
SUBSCRIBER SUBSCRIBER_TYPE
}

D. CREATE TABLE SUBSCRIBER_TYPE {
course_id timeuuid,
emails map,
name text
}

CREATE TABLE HADOOPEXAM {
course_id timeuuid,
title text,
Category map,
SUBSCRIBER SUBSCRIBER_TYPE
}


1. A,B
2. B,C
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4. A,D
5. B,D


Question : Cassandra counters are always % accurate.

1. True
2. False


Question : Which of the following command will help you to run a cql file storing all cql commands?

1. SOURCE filename.cql

2. EXECUTE filename.cql

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4. FIRE filename.cql

5. COMMIT filename.cql




Question : . Which of the following is correct statement with regards to Counter?

A. A counter column value is a 64-bit signed integer.
B. You cannot set the value of a counter, which supports two operations: increment and decrement.
C. To generate sequential numbers for surrogate keys, use the counter type.
D. You can create an index on a counter column


1. A,B
2. B,C
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4. A,D
5. B,D


Question : You have been given below table definition

CREATE TABLE reviews (
review_id text,
downcount int,
upcount int,
creation_date timestamp,
PRIMARY KEY (review_id)
)

Now you want to update the upcount value by 1, hence you run the following query

update reviews set upcount = upcount +1 where review_id='123456';

What do you expect, out of this ?

1. It will successfully increment upcount by 1 for review_id='123456'

2. Update will be successful, but upcount will not be incremented by 1.

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4. Creation of table statement will fail.