Fanout exchange (broadcast) in RabbitMQ - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output when a message is published to a fanout exchange with two queues bound?

Assume a fanout exchange named logs has two queues queue1 and queue2 bound to it. If a message "Hello" is published to logs, what will be the result?

RabbitMQ

rabbitmqadmin publish exchange=logs routing_key= payload="Hello"

A Only queue1 receives the message "Hello"

B Both queue1 and queue2 receive the message "Hello"

C Only queue2 receives the message "Hello"

D No queue receives the message because routing_key is empty

💡 Hint

Fanout exchanges ignore routing keys and broadcast messages to all bound queues.

Fanout exchanges send messages to all queues bound to them regardless of routing keys. So both queues get the message.

🧠 Conceptual

intermediate

Which statement correctly describes a fanout exchange?

Choose the correct description of how a fanout exchange works in RabbitMQ.

A It stores messages until a consumer connects, then sends them.

B It routes messages to queues based on exact matching routing keys.

C It broadcasts messages to all queues bound to it, ignoring routing keys.

D It routes messages to queues based on pattern matching routing keys.

💡 Hint

Think about how a broadcast works in real life.

Fanout exchanges ignore routing keys and send messages to all queues bound to them, acting like a broadcast.

❓ Configuration

advanced

Which configuration correctly declares a fanout exchange named 'broadcast_logs' using rabbitmqctl?

Select the correct command to declare a fanout exchange named broadcast_logs using rabbitmqctl.

A rabbitmqadmin declare exchange name=broadcast_logs type=fanout

B rabbitmqadmin add exchange broadcast_logs fanout

C rabbitmqctl declare exchange name=broadcast_logs type=fanout

D rabbitmqctl add_exchange broadcast_logs fanout

💡 Hint

Remember which tool is used for declaring exchanges and the correct syntax.

rabbitmqadmin is used to declare exchanges with the syntax declare exchange name=... type=.... rabbitmqctl does not support this command.

❓ Troubleshoot

advanced

Why does a message published to a fanout exchange not reach any queue?

You have a fanout exchange named logs and a queue queue1 bound to it. You publish a message but queue1 does not receive it. What could be the reason?

A The queue <code>queue1</code> is not bound to the exchange <code>logs</code> properly.

B The routing key used in publishing does not match the queue name.

C Fanout exchanges require a routing key to deliver messages.

D The message was too large and was dropped by the exchange.

💡 Hint

Check the bindings between exchange and queue.

If the queue is not bound to the fanout exchange, it will not receive any messages because fanout exchanges deliver only to bound queues.

✅ Best Practice

expert

What is the best practice when using fanout exchanges for broadcasting logs to multiple services?

When designing a system that broadcasts log messages to multiple services using a fanout exchange, which practice is recommended?

A Bind all services to the same queue to simplify message consumption.

B Use direct exchanges instead of fanout to control routing precisely.

C Publish messages with routing keys matching each service name.

D Use separate queues for each service bound to the fanout exchange to avoid message loss.

💡 Hint

Think about how message delivery and consumption work with multiple consumers.

Each service should have its own queue bound to the fanout exchange to ensure all receive the broadcast messages independently without competing for the same queue.