Cluster creation in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the main purpose of creating a Redis cluster?

Redis clusters are used to:

A Distribute data across multiple nodes for scalability and fault tolerance

B Encrypt data automatically without configuration

C Store data only on a single node for faster access

D Backup data to external storage automatically

💡 Hint

Think about why multiple Redis nodes work together in a cluster.

A Redis cluster distributes data across nodes to handle more data and continue working if some nodes fail.

❓ query_result

intermediate

What is the output of the command CLUSTER INFO on a healthy Redis cluster?

Given a healthy Redis cluster, what does the CLUSTER INFO command return for the cluster_state field?

Redis

CLUSTER INFO

A cluster_state:fail

B cluster_state:unknown

C cluster_state:ok

D cluster_state:down

💡 Hint

Healthy means the cluster is working fine.

The cluster_state field shows ok when the cluster is healthy and operational.

📝 Syntax

advanced

Which command correctly adds a node to an existing Redis cluster?

Select the correct Redis CLI command to add a new node with IP 192.168.1.10 and port 7003 to an existing cluster.

A redis-cli --cluster create 192.168.1.10:7003 192.168.1.1:7000

B redis-cli --cluster add-node 192.168.1.10:7003 192.168.1.1:7000

C redis-cli --cluster join 192.168.1.10:7003 192.168.1.1:7000

D redis-cli --cluster attach 192.168.1.10:7003 192.168.1.1:7000

💡 Hint

Adding a node uses the add-node option.

The --cluster add-node command adds a new node to an existing cluster by specifying the new node and an existing cluster node.

❓ optimization

advanced

How can you optimize slot allocation when creating a Redis cluster with 3 nodes?

You want to create a Redis cluster with 3 nodes and distribute slots evenly. Which command option ensures balanced slot allocation?

A redis-cli --cluster create 192.168.1.1:7000 192.168.1.2:7000 192.168.1.3:7000 --cluster-replicas 0

B redis-cli --cluster create 192.168.1.1:7000 192.168.1.2:7000 192.168.1.3:7000 --cluster-assign-slots 0

C redis-cli --cluster create 192.168.1.1:7000 192.168.1.2:7000 192.168.1.3:7000 --cluster-replicas 1

D redis-cli --cluster create 192.168.1.1:7000 192.168.1.2:7000 192.168.1.3:7000 --cluster-slots 16384

💡 Hint

Think about how replicas affect slot distribution.

Using --cluster-replicas 0 creates a cluster with no replicas, so slots are evenly distributed among the 3 nodes.

🔧 Debug

expert

Why does the command redis-cli --cluster create 192.168.1.1:7000 192.168.1.2:7000 fail?

You try to create a Redis cluster with only two nodes using the command above. Why does it fail?

A Redis cluster cannot be created on ports below 7000

B The command syntax is incorrect; it needs a <code>--cluster-replicas</code> option

C The IP addresses must be localhost for cluster creation

D Redis cluster requires at least 3 master nodes to form a valid cluster

💡 Hint

Think about the minimum number of master nodes for a Redis cluster.

A Redis cluster requires at least 3 master nodes to ensure data partitioning and fault tolerance. Two nodes are insufficient.