Cassandra Practice Test

What is the purpose of Hinted Handoff in Cassandra?

1. To replicate data across multiple nodes

2. To maintain consistency when a node is down

3. To perform repairs on data replicas

4. To execute read operations more efficiently

The correct answer is: To maintain consistency when a node is down

The purpose of Hinted Handoff in Cassandra is primarily to maintain consistency when a node is down. Hinted Handoff is a mechanism that allows a node to temporarily store data intended for another node that is currently unavailable due to failure or maintenance. When a write operation occurs, if the target node is down, the coordinator node will deliver the data to a "hint" storage for that unavailable node. Once the downed node comes back online, the hints are delivered, ensuring that the data is eventually consistent across all replicas. This approach helps minimize data loss and ensures that reads from the cluster remain consistent even if some nodes are temporarily unavailable. It is particularly valuable in a distributed environment where nodes can frequently become unreachable, either due to network issues or hardware failures. In contrast, other choices focus on different aspects of Cassandra’s functionality. Replicating data across multiple nodes is part of the overall data modeling strategy, while executing efficient read operations relates to how data is retrieved from nodes. Performing repairs on data replicas is a separate process that ensures data integrity and consistency in a more proactive manner, rather than focusing on the immediate need to maintain availability during a failure.