# Professional-Cloud-Architect — Question 428

**Type:** multiple_choice
**Topics:** topic_1

## Question

You are developing a globally scaled frontend for a legacy streaming backend data API. This API expects events in strict chronological order with no repeat data for proper processing.
Which products should you deploy to ensure guaranteed-once FIFO (first-in, first-out) delivery of data?

## Correct Answer

_See scenario._

## Explanation

I believe the answer is B. "Pub/Sub doesn't provide guarantees about the order of message delivery. Strict message ordering can be achieved with buffering, often using Dataflow." https://cloud.google.com/solutions/data-lifecycle-cloud-platform

**Reference:** examtopics_top_comment

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Source: https://hiexam.net/q/google/Professional-Cloud-Architect/428  
Practice (tracked): https://hiexam.net/study/Professional-Cloud-Architect/practice