The answer is the account's Lambda concurrency limit has been reached due to the increased reserved concurrency. This occurs because AWS Lambda enforces a soft account-level concurrency limit (typically 1,000 by default) that is shared across all functions in a region; when you raise reserved concurrency for one function from 5 to 10, you are effectively locking 10 units of that shared pool exclusively for that function, leaving fewer units available for other functions. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this question tests your understanding of how reserved concurrency interacts with account limits—a common trap is assuming that increasing reserved concurrency always increases throughput, when in fact it can starve other functions and trigger RateExceeded errors across the account. The key insight is that reserved concurrency guarantees capacity for your function but does not raise the overall account ceiling, so throttling occurs when the sum of all reserved concurrency values plus the burst concurrency of other functions exceeds the account limit. Memory tip: think of reserved concurrency as a reserved parking spot—it guarantees your car a space, but if the lot is full, other cars get blocked out.
DOP-C02 Incident and Event Response Practice Question
This DOP-C02 practice question tests your understanding of incident and event response. 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 AWS Lambda functions to process messages from an Amazon SQS queue. The Lambda function is configured with a reserved concurrency of 5. The SQS queue has a large backlog of messages, and the Lambda function is processing them slowly. The DevOps team wants to increase throughput without making changes to the Lambda code. The team decides to increase the reserved concurrency to 10. However, after the change, the Lambda function starts to experience throttling errors (RateExceeded). The team also notices that other Lambda functions in the same account are also being throttled. What is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The account's Lambda concurrency limit has been reached due to the increased reserved concurrency.
Option B is correct because the account-level Lambda concurrency limit may be reached. Increasing reserved concurrency for one function reduces the pool available for others. Option A is wrong because SQS batch size does not cause throttling. Option C is wrong because SQS polling interval is controlled by Lambda. Option D is wrong because IAM permissions would cause access denied errors, not throttling.
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 SQS queue's polling interval is too high, causing Lambda to poll infrequently.
Why it's wrong here
Lambda polls SQS automatically; interval is not configurable.
✓
The account's Lambda concurrency limit has been reached due to the increased reserved concurrency.
Why this is correct
Reserved concurrency consumes from the account limit.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Lambda function's execution role does not have permission to invoke the function.
Why it's wrong here
Role issues cause access denied, not throttling.
✗
The SQS queue's visibility timeout is too short, causing messages to be processed multiple times.
Why it's wrong here
Visibility timeout affects message duplication, not throttling.
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 DOP-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.
Incident and Event Response — This question tests Incident and Event Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The account's Lambda concurrency limit has been reached due to the increased reserved concurrency. — Option B is correct because the account-level Lambda concurrency limit may be reached. Increasing reserved concurrency for one function reduces the pool available for others. Option A is wrong because SQS batch size does not cause throttling. Option C is wrong because SQS polling interval is controlled by Lambda. Option D is wrong because IAM permissions would cause access denied errors, not throttling.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses AWS Lambda functions to process events from Amazon SQS. Recently, the Lambda function has been throttled, causing messages to accumulate in the dead-letter queue (DLQ). The function’s reserved concurrency is set to 100, and the account’s regional concurrency limit is 1000. What is the MOST likely cause of the throttling?
hard
✓ A.The function’s concurrency is fully utilized due to long-running invocations
B.The Lambda function has a cold start issue
C.The SQS queue is not configured as a FIFO queue
D.The reserved concurrency is set too high, exceeding the account limit
Why A: Option D is correct because if the function’s reserved concurrency is 100 and the account-level limit is 1000, throttling could be due to the function exhausting its own concurrency if it has long-running invocations. Option A is wrong because 100 reserved is not above the account limit. Option B is wrong because SQS standard queue does not require FIFO. Option C is wrong because cold starts cause latency but not throttling.
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This DOP-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 DOP-C02 exam.
Question Discussion
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