The answer is that read capacity auto-scaling cannot keep up with sudden traffic spikes, causing throttling and a fallback to eventually consistent reads. This is the most likely cause of DynamoDB strongly consistent reads returning stale data due to throttling, because when read requests exceed the provisioned capacity—especially above the maximum auto-scaling limit of 10,000 RCUs—the service throttles the request, and the AWS SDK automatically retries using eventually consistent reads, which can return stale data. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how DynamoDB’s consistency model interacts with capacity management; a common trap is assuming strongly consistent reads are immune to throttling, but they simply fail or degrade when capacity is exhausted. A helpful memory tip: “Throttle forces fallback—strong consistency is not a guarantee against stale data when capacity caps out.”
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 Amazon DynamoDB as the primary data store for a real-time application. The data engineer observes that some read requests are returning stale data, even though the application uses strongly consistent reads. The table has auto-scaling enabled with a maximum read capacity of 10,000 RCUs. The observed read traffic averages 8,000 RCUs but occasionally spikes to 12,000 RCUs. What is the most likely cause of the stale reads?
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.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Read capacity auto-scaling cannot keep up with sudden traffic spikes, causing throttling and fallback to eventually consistent reads.
Option C is correct because strongly consistent reads can return stale data if the application is throttled due to insufficient read capacity. During spikes above the maximum auto-scaling limit (10,000 RCUs), requests may be throttled, and the SDK may retry with eventually consistent reads, returning stale data. Option A is incorrect because global tables with eventually consistent reads would not affect a single table. Option B is incorrect because DynamoDB Accelerator (DAX) provides eventual consistency by default, but strongly consistent reads would bypass DAX. Option D is incorrect because write sharding does not cause stale reads on the same table.
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.
✓
Read capacity auto-scaling cannot keep up with sudden traffic spikes, causing throttling and fallback to eventually consistent reads.
Why this is correct
Throttling can cause fallback to eventual consistency.
Clue confirmation
The clue words "most likely", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The application uses write sharding, causing read-after-write inconsistencies.
Why it's wrong here
Write sharding does not affect read consistency.
✗
The application is using DynamoDB Accelerator (DAX) which caches data and may return stale values.
Why it's wrong here
DAX is a cache; strongly consistent reads bypass DAX.
✗
The table is part of a DynamoDB global table, and the application reads from a replica in a different region.
Why it's wrong here
Global tables offer eventually consistent reads, but the app uses strongly consistent reads.
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 DEA-C01 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.
Data Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Read capacity auto-scaling cannot keep up with sudden traffic spikes, causing throttling and fallback to eventually consistent reads. — Option C is correct because strongly consistent reads can return stale data if the application is throttled due to insufficient read capacity. During spikes above the maximum auto-scaling limit (10,000 RCUs), requests may be throttled, and the SDK may retry with eventually consistent reads, returning stale data. Option A is incorrect because global tables with eventually consistent reads would not affect a single table. Option B is incorrect because DynamoDB Accelerator (DAX) provides eventual consistency by default, but strongly consistent reads would bypass DAX. Option D is incorrect because write sharding does not cause stale reads on the same table.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 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", "primary". 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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Question Discussion
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