- A
Lambda rejects the messages and sends them to the dead-letter queue.
Why wrong: Messages are not rejected; they remain in the queue until processed.
- B
Lambda automatically scales up to 1000 concurrent executions to process all messages quickly.
Why wrong: Reserved concurrency limits the maximum concurrent executions to 10, so it cannot scale beyond that.
- C
Lambda increases the reserved concurrency to accommodate the burst.
Why wrong: Reserved concurrency is a fixed limit set by the user; Lambda does not change it automatically.
- D
Lambda processes up to 10 messages concurrently, and the rest remain in the queue until processing capacity is available.
With reserved concurrency of 10, only 10 functions run at a time; remaining messages wait in the queue.
Question 1,198 of 1,616
Lambda Reserved Concurrency and SQS
This DVA-C02 practice question tests your understanding of development with aws services. 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 is using AWS Lambda to process messages from an Amazon SQS queue. The Lambda function is configured with a reserved concurrency of 10. The SQS queue receives a burst of 1000 messages. The Lambda function processes each message in about 5 seconds. What is the most likely behavior of the system?
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 choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Lambda processes up to 10 messages concurrently, and the rest remain in the queue until processing capacity is available.
Option D is correct because Lambda's reserved concurrency of 10 caps the maximum number of concurrent executions. When the SQS queue receives 1000 messages, Lambda polls the queue and invokes the function with up to 10 messages at a time (based on batch size, default 1). The remaining messages stay in the queue and are retried after the visibility timeout expires, as Lambda processes messages in batches limited by the reserved concurrency.
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.
- ✗
Lambda rejects the messages and sends them to the dead-letter queue.
Why it's wrong here
Messages are not rejected; they remain in the queue until processed.
- ✗
Lambda automatically scales up to 1000 concurrent executions to process all messages quickly.
Why it's wrong here
Reserved concurrency limits the maximum concurrent executions to 10, so it cannot scale beyond that.
- ✗
Lambda increases the reserved concurrency to accommodate the burst.
Why it's wrong here
Reserved concurrency is a fixed limit set by the user; Lambda does not change it automatically.
- ✓
Lambda processes up to 10 messages concurrently, and the rest remain in the queue until processing capacity is available.
Why this is correct
With reserved concurrency of 10, only 10 functions run at a time; remaining messages wait in the queue.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume Lambda automatically scales to handle any burst, but reserved concurrency explicitly limits scaling, and the exam tests understanding that this limit is enforced regardless of queue depth.
Detailed technical explanation
How to think about this question
Lambda uses event source mapping to poll SQS queues, with a maximum of 5 concurrent polls per function (scaling up to 60 polls per minute per partition). With reserved concurrency of 10, the function can only process 10 invocations simultaneously, so messages exceeding that capacity remain in the queue and are subject to the visibility timeout (default 30 seconds). In real-world scenarios, this can lead to increased latency and potential throttling if the queue backlog grows faster than processing capacity.
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.
TExam Day Tips
- 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.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Lambda processes up to 10 messages concurrently, and the rest remain in the queue until processing capacity is available. — Option D is correct because Lambda's reserved concurrency of 10 caps the maximum number of concurrent executions. When the SQS queue receives 1000 messages, Lambda polls the queue and invokes the function with up to 10 messages at a time (based on batch size, default 1). The remaining messages stay in the queue and are retried after the visibility timeout expires, as Lambda processes messages in batches limited by the reserved concurrency.
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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.
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Last reviewed: Jul 4, 2026
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.
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