- A
DynamoDB Accelerator (DAX)
Caches reads, reducing the number of read capacity units consumed.
- B
DynamoDB Global Tables
Why wrong: Global Tables replicate data across regions.
- C
DynamoDB Auto Scaling
Why wrong: Auto scaling adjusts throughput, not cost per read.
- D
Time to Live (TTL)
Why wrong: TTL automatically deletes items.
Question 740 of 1,616
DynamoDB Accelerator (DAX) — Reducing Read Costs | AWS Developer Associate Explained
This DVA-C02 practice question tests your understanding of development with aws services. 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 developer is building an application that uses Amazon DynamoDB as a data store. The application reads the same item frequently but writes rarely. The developer wants to reduce read costs. Which DynamoDB feature should the developer use?
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
✓
DynamoDB Accelerator (DAX)
DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency from single-digit milliseconds to microseconds. Since the application reads the same item frequently but writes rarely, DAX can serve repeated read requests from its cache, significantly reducing the number of read capacity units consumed against the DynamoDB table and thus lowering read costs.
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.
- ✓
DynamoDB Accelerator (DAX)
Why this is correct
Caches reads, reducing the number of read capacity units consumed.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
DynamoDB Global Tables
Why it's wrong here
Global Tables replicate data across regions.
- ✗
DynamoDB Auto Scaling
Why it's wrong here
Auto scaling adjusts throughput, not cost per read.
- ✗
Time to Live (TTL)
Why it's wrong here
TTL automatically deletes items.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse DAX with ElastiCache or assume that Auto Scaling reduces costs, but DAX is the only DynamoDB-native service that directly reduces read costs by caching frequently accessed items.
Detailed technical explanation
How to think about this question
DAX maintains a write-through cache that is strongly consistent for cached items, but it can serve eventually consistent reads directly from the cache without consuming table read capacity. In a read-heavy, write-light workload, DAX can reduce read costs by up to 90% because cached reads do not count against the table's provisioned read capacity units. The cache uses an LRU eviction policy, so frequently accessed items remain cached while infrequently accessed items are evicted.
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?
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: DynamoDB Accelerator (DAX) — DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency from single-digit milliseconds to microseconds. Since the application reads the same item frequently but writes rarely, DAX can serve repeated read requests from its cache, significantly reducing the number of read capacity units consumed against the DynamoDB table and thus lowering read costs.
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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Last reviewed: Jul 4, 2026
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