Question-13: Select correct statement which applies to replication factor for Cassandra.

1. Replication factor 1 means each column will be separately copied on every node in cluster from a Row.
2. A replication factor 2 means two copies of each row, where each copy is on different node.
3. First replica is always considered primary replica, if node crashes which holds primary replica then second replica become primary.
4. You should not set replication factor more than number of nodes in the cluster.

Ans: B, D

Exp: Replication factor decide how many copies should be kept for each row in a Cassandra cluster. In your Cassandra cluster if you have only one node then there is no point of having replication factor more than 1. Similarly, if there are two nodes then you can have replication factor as 2. Hence, you should not set Replication factor more than number of nodes in cluster. Hence, option-4 is correct.

In the Cassandra each row has equal priority there is no concept of primary and secondary replica. Hence, option-3 is not correct.

Replication factor always talk about the entire row and not for individual column. Hence, option-1 is out. And option-2 is correct.