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Question 381 of 1,616

Troubleshooting and Optimization →mediumMultiple ChoiceObjective-mapped

Quick Answer

The correct answer is to implement exponential backoff and retry in the Lambda function code for DynamoDB API calls. This is the right approach because even with DynamoDB on-demand capacity mode, the service can still throttle requests when they exceed the table’s burst capacity or when a hot partition creates uneven traffic, and exponential backoff directly addresses Lambda DynamoDB throttling by progressively increasing the wait time between retries, allowing the database to recover and reducing the retry storm. On the AWS Certified Developer Associate DVA-C02 exam, this question tests your understanding that throttling is not solely a capacity issue—it can occur at the partition level—and that application-level retry logic is the developer’s responsibility, not just relying on AWS service defaults. A common trap is assuming on-demand mode eliminates all throttling or that increasing Lambda concurrency will help, but that can actually worsen the problem. Memory tip: think “back off to break through”—exponential backoff gives DynamoDB breathing room to handle your writes.

DVA-C02 Troubleshooting and Optimization Practice Question

This DVA-C02 practice question tests your understanding of troubleshooting and optimization. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 notices that an AWS Lambda function processing S3 events is being retried frequently due to throttling errors from Amazon DynamoDB. The function writes records to a DynamoDB table and has reserved concurrency set to 100. The DynamoDB table uses on-demand capacity mode. What should the developer do to reduce retries and improve overall throughput?

Question 1mediummultiple choice

Full question →

A
Increase the Lambda function's reserved concurrency to 500.
Why wrong: Increasing concurrency may make the problem worse by sending more concurrent requests to DynamoDB, leading to more throttling.
B
Implement exponential backoff and retry in the Lambda function code for DynamoDB API calls.
Exponential backoff and retry automatically handle throttling errors by retrying with increasing delays, reducing the chance of repeated failures.
C
Disable the Lambda function's S3 event source mapping and use Amazon SQS to buffer events.
Why wrong: While SQS can help decouple and retry, it adds complexity and latency; the immediate issue of DynamoDB throttling is better addressed with retry logic within the function.
D
Switch the DynamoDB table to provisioned capacity with a high write capacity unit setting.
Why wrong: Provisioned capacity requires manual scaling and may lead to over-provisioning or under-provisioning; on-demand is already suitable for variable workloads.

Full breakdown with real-world context →

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

✓

Implement exponential backoff and retry in the Lambda function code for DynamoDB API calls.

Option B is correct because implementing exponential backoff and retry in the Lambda function code for DynamoDB API calls directly addresses the throttling errors. Even with on-demand capacity, DynamoDB can throttle requests if they exceed the table's burst capacity or if there are hot partitions. Exponential backoff reduces the retry rate, allowing DynamoDB to recover and improving overall throughput without changing the Lambda concurrency or capacity mode.

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.

✗
Increase the Lambda function's reserved concurrency to 500.
Why it's wrong here
Increasing concurrency may make the problem worse by sending more concurrent requests to DynamoDB, leading to more throttling.
✓
Implement exponential backoff and retry in the Lambda function code for DynamoDB API calls.
Why this is correct
Exponential backoff and retry automatically handle throttling errors by retrying with increasing delays, reducing the chance of repeated failures.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disable the Lambda function's S3 event source mapping and use Amazon SQS to buffer events.
Why it's wrong here
While SQS can help decouple and retry, it adds complexity and latency; the immediate issue of DynamoDB throttling is better addressed with retry logic within the function.
✗
Switch the DynamoDB table to provisioned capacity with a high write capacity unit setting.
Why it's wrong here
Provisioned capacity requires manual scaling and may lead to over-provisioning or under-provisioning; on-demand is already suitable for variable workloads.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume increasing Lambda concurrency or switching to provisioned capacity will solve throttling, but the real issue is the retry strategy at the application layer, not the infrastructure scaling.

Detailed technical explanation

How to think about this question

DynamoDB on-demand capacity mode can throttle requests if they exceed the table's previously observed peak traffic by more than double, or if a single partition receives more than 1,000 write capacity units per second. Exponential backoff with jitter is recommended by AWS to handle throttling gracefully, as it spreads retries over time and prevents thundering herd problems. The AWS SDK for Lambda (boto3) automatically implements exponential backoff for DynamoDB calls, but if custom code uses low-level API calls, developers must implement it manually.

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.

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?

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: Implement exponential backoff and retry in the Lambda function code for DynamoDB API calls. — Option B is correct because implementing exponential backoff and retry in the Lambda function code for DynamoDB API calls directly addresses the throttling errors. Even with on-demand capacity, DynamoDB can throttle requests if they exceed the table's burst capacity or if there are hot partitions. Exponential backoff reduces the retry rate, allowing DynamoDB to recover and improving overall throughput without changing the Lambda concurrency or capacity mode.

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.

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.