Back-End Development Message Queues and Event-Driven Architecture

Question 1

What is a message queue primarily used for in back-end systems?

Accepted Answer

Decoupling services and enabling asynchronous communication

Answer

Storing user session data

Answer

Caching database query results

Answer

Managing HTTP request routing

Question 2

In a publish-subscribe (pub/sub) pattern, what is a 'subscriber'?

Accepted Answer

A service that receives and processes messages from a topic

Answer

A service that writes messages to a queue

Answer

A load balancer that distributes messages

Answer

A database that stores message metadata

Question 3

What is the key difference between a point-to-point queue and a pub/sub topic?

Accepted Answer

A queue delivers each message to one consumer; a topic delivers to all subscribers

Answer

Queues are faster than topics

Answer

Topics require acknowledgment but queues do not

Answer

Queues support only string messages while topics support binary

Question 4

What does a message acknowledgment (ACK) tell the broker in a queue system?

Accepted Answer

The consumer signals it has successfully processed the message

Answer

The producer confirms the message was created successfully

Answer

The broker confirms it has sufficient disk space

Answer

The load balancer confirms message routing completed

Question 5

What is a Dead Letter Queue (DLQ) used for?

Accepted Answer

Holding messages that failed processing after the maximum retry limit

Answer

Storing high-priority urgent messages

Answer

Archiving all messages for compliance auditing

Answer

Buffering messages during peak traffic spikes

Question 6

Which messaging pattern is best suited for distributing workload across multiple parallel workers?

Accepted Answer

Competing Consumers

Answer

Publish/Subscribe

Answer

Request/Reply

Answer

Fan-out Exchange

Question 7

What is the purpose of message durability in a message broker?

Accepted Answer

Ensuring messages survive broker restarts by persisting them to disk

Answer

Encrypting messages during transit

Answer

Compressing messages for efficient network transfer

Answer

Routing messages to the consumer with the lowest latency