Question 32
Domain 5Which feature of Google Cloud Pub/Sub ensures that messages are delivered at least once to subscribers?
Correct answer: C
Explanation
Google Cloud Pub/Sub provides "at-least-once delivery," meaning each message is sent to subscribers one or more times until it is acknowledged. This delivery model helps ensure messages are not lost, even if retries or failures occur during delivery.
Why each option is right or wrong
A. Message duplication
B. Exactly-once delivery.
C. At-least-once delivery
Google Cloud Pub/Sub’s subscription delivery model is defined to retry any message that is not acknowledged within the ack deadline, so the service may redeliver the same message after transient failures. Under the Pub/Sub subscription semantics, a message remains eligible for redelivery until an acknowledgment is received, which is why the service guarantees delivery of each published message one or more times rather than exactly once.
D. Load balancing