PDE Designing data processing systems Practice Question
This PDE practice question tests your understanding of designing data processing systems. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company uses Cloud Pub/Sub with pull subscriptions to process orders. The application requires at-least-once delivery and the ability to process orders in order per customer_id. Which THREE features should they configure? (Choose three.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "least"
Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure a dead letter topic
Correct answers are B, C, and E. Enabling ordering keys ensures messages with the same key are delivered in order. Setting exactly-once delivery on subscriptions provides at-least-once with deduplication; but exactly-once delivery on subscription actually reduces duplicates. However, the question says at-least-once, so exactly-once delivery would be too strong? Actually, exactly-once delivery on subscription ensures no duplicates, so it's even better. But if they need at-least-once, they could enable it and it still satisfies. Dead letter topics allow failed messages to be isolated and reprocessed later without blocking. A (ackDeadline of 600 seconds) is too long. D (using a push subscription) does not inherently improve ordering.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Configure a dead letter topic
Why this is correct
Allows failed messages to be stored without blocking subsequent messages.
Clue confirmation
The clue word "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a push subscription with a HTTPS endpoint
Why it's wrong here
Push subscriptions can deliver messages, but ordering is achieved via configuration.
✓
Enable ordering keys on the topic
Why this is correct
Required for ordered delivery per key.
Clue confirmation
The clue word "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable message ordering on the subscription
Why this is correct
Ensures messages are delivered in order per key.
Clue confirmation
The clue word "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set the subscription's ackDeadline to 600 seconds
Why it's wrong here
Long ack deadline may cause delays but not necessary for ordering.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which PDE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Designing data processing systems — This question tests Designing data processing systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure a dead letter topic — Correct answers are B, C, and E. Enabling ordering keys ensures messages with the same key are delivered in order. Setting exactly-once delivery on subscriptions provides at-least-once with deduplication; but exactly-once delivery on subscription actually reduces duplicates. However, the question says at-least-once, so exactly-once delivery would be too strong? Actually, exactly-once delivery on subscription ensures no duplicates, so it's even better. But if they need at-least-once, they could enable it and it still satisfies. Dead letter topics allow failed messages to be isolated and reprocessed later without blocking. A (ackDeadline of 600 seconds) is too long. D (using a push subscription) does not inherently improve ordering.
What should I do if I get this PDE question wrong?
Identify which PDE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "least". You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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