Message Queue

Question 1

What is the main difference between pub/sub and point-to-point messaging?

Accepted Answer

Number of intended recipients — In pub/sub, messages are broadcast to all subscribers of a topic. In point-to-point, each message is consumed by exactly one consumer.

Question 2

A message queue enables ___ communication between services.

Accepted Answer

Asynchronous — Producers send messages without waiting for consumers; the queue buffers them, decoupling the two in time and load.

Question 3

In the producer-consumer pattern, the queue…

Accepted Answer

Buffers messages for consumers — The queue absorbs bursts and rate differences, letting producers and consumers operate at their own pace.

Question 4

A key benefit of message queues is…

Accepted Answer

Decoupling of services — Decoupling improves resilience and scalability: a slow or down consumer doesn't block producers, and components scale independently.

Question 5

Message queues help handle traffic spikes by…

Accepted Answer

Buffering bursts for steady flow — The queue smooths spikes: work piles up temporarily and is drained at the consumers' pace rather than overwhelming them.

Question 6

'At-least-once' delivery means a message is…

Accepted Answer

Delivered one or more times — To guarantee no loss, the system may redeliver on uncertain acknowledgment, so consumers must handle duplicates.

Question 7

Because at-least-once delivery can cause duplicates, consumers should be…

Accepted Answer

Idempotent, so duplicates are safe — Idempotent processing (e.g. dedup by message ID) makes duplicate deliveries safe — essential for reliable queue consumers.

Question 8

A Dead Letter Queue (DLQ) is used to…

Accepted Answer

Hold repeatedly failing messages — Poison messages that can't be processed after retries are moved to a DLQ so they don't block the queue and can be debugged.

Question 9

In point-to-point (queue) semantics, each message is consumed by…

Accepted Answer

Exactly one consumer — Competing consumers share the work; each message goes to a single consumer — used to parallelize processing of a task stream.

Question 10

In publish-subscribe (pub/sub) semantics, each message is delivered to…

Accepted Answer

All interested subscribers — Pub/sub broadcasts: every subscriber gets a copy, enabling fan-out to multiple independent consumers (e.g. analytics + notifications).

Queue or pub/sub?

Test your knowledge

What is the main difference between pub/sub and point-to-point messaging?

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