Mirrored queues for redundancy in RabbitMQ - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Mirrored Queues in RabbitMQ

What is the primary purpose of using mirrored queues in RabbitMQ?

A To increase message throughput by parallel processing

B To replicate messages across multiple nodes for high availability

C To encrypt messages during transmission

D To compress messages to save storage space

💡 Hint

Think about what redundancy means in message queuing.

Mirrored queues replicate messages across nodes to ensure availability if one node fails.

💻 Command Output

intermediate

Check Mirrored Queue Status

What is the output of the following RabbitMQ command when checking the status of a mirrored queue named task_queue?

rabbitmqctl list_queues name policy

A Error: queue not found

B task_queue lazy

C task_queue none

D task_queue all

💡 Hint

Mirrored queues use the all policy by default.

The all policy means the queue is mirrored across all nodes.

❓ Configuration

advanced

Configuring a Mirrored Queue Policy

Which of the following commands correctly sets a policy to mirror all queues on all nodes in RabbitMQ?

A rabbitmqctl set_policy ha-all ".*" '{"ha-mode":"all"}'

B rabbitmqctl set_policy ha-all ".*" '{"ha-mode":"nodes"}'

C rabbitmqctl set_policy ha-all ".*" '{"ha-mode":"lazy"}'

D rabbitmqctl set_policy ha-all ".*" '{"ha-mode":"exactly", "ha-params":2}'

💡 Hint

The ha-mode must be set to all to mirror on all nodes.

The command sets a policy named ha-all to mirror all queues matching .* on all nodes.

❓ Troubleshoot

advanced

Troubleshooting Mirrored Queue Failover

You notice that after a node failure, messages are lost from a mirrored queue. Which of the following is the most likely cause?

A The RabbitMQ service was restarted on all nodes simultaneously

B The queue was not configured with a mirrored policy

C The messages were published with <code>delivery_mode=1</code> (non-persistent)

D The consumers were not connected to the master node

💡 Hint

Consider message durability and persistence in RabbitMQ.

Non-persistent messages (delivery_mode=1) are not saved to disk and can be lost on node failure even with mirrored queues.

🔀 Workflow

expert

Steps to Create and Verify a Mirrored Queue

Arrange the steps in the correct order to create a mirrored queue named logs and verify its mirroring status in RabbitMQ.

A 1,2,3,4

B 2,1,4,3

C 1,2,4,3

D 2,4,1,3

💡 Hint

Policies must be set before queue declaration to apply mirroring.

First set the mirroring policy, then declare the queue so it inherits the policy, verify the policy, then publish messages.