The answer is that the function is not receiving any invocations because it has no concurrency available. Setting Lambda reserved concurrency to 0 effectively blocks all execution, as the function is allocated zero dedicated capacity and cannot scale to handle any requests. This means the SQS queue messages will remain unprocessed, eventually failing or moving to a dead-letter queue, rather than being throttled or timing out. On the AWS Certified Developer Associate DVA-C02 exam, this concept tests your understanding that reserved concurrency acts as a hard limit on concurrent executions, and a value of 0 is a kill switch, not a scaling throttle. A common trap is confusing a concurrency of 0 with throttling—throttling implies some invocations succeed, but 0 means none ever start. Remember the memory tip: “Zero concurrency, zero executions.”
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 developer has an AWS Lambda function that processes messages from an Amazon SQS queue. The function is experiencing high invocation errors. The developer sees that the function's reserved concurrency is set to 0. What is the impact?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The function is not receiving any invocations because it has no concurrency available.
Reserved concurrency of 0 means the function cannot scale, so no invocations occur. This causes all messages to stay in the queue or go to DLQ. Option B is correct. Option A is wrong because throttling is not the main issue. Option C is wrong because the function never runs. Option D is wrong because concurrency limit is 0.
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.
✗
The function's memory is insufficient, causing out-of-memory errors.
Why it's wrong here
Memory allocation doesn't matter if the function isn't invoked.
✗
The function is throttled due to high request volume.
Why it's wrong here
Throttling would occur only if requests exceed concurrency limit, but limit is 0 so no requests are processed.
✗
The function's code has an error causing it to fail.
Why it's wrong here
The function is never executed.
✓
The function is not receiving any invocations because it has no concurrency available.
Why this is correct
With reserved concurrency 0, the function cannot be invoked.
Related concept
Read the scenario before looking for a memorised answer.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which DVA-C02 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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The function is not receiving any invocations because it has no concurrency available. — Reserved concurrency of 0 means the function cannot scale, so no invocations occur. This causes all messages to stay in the queue or go to DLQ. Option B is correct. Option A is wrong because throttling is not the main issue. Option C is wrong because the function never runs. Option D is wrong because concurrency limit is 0.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-C02 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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This DVA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DVA-C02 exam.
Question Discussion
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