DVA-C02 Development with AWS Services Practice Question
A developer is using AWS X-Ray to trace a serverless application. The application uses an AWS Lambda function to query a DynamoDB table. The trace shows that the DynamoDB subsegment takes a significant portion of the total response time. The developer wants to reduce the DynamoDB query latency. Which service should the developer integrate with the Lambda function to achieve the lowest latency for repeated read queries?
⚠ Common exam trap
Test-takers frequently choose ElastiCache for Redis because it is a well-known caching solution, but they overlook that DAX is purpose-built for DynamoDB and provides lower latency with zero application-level cache management, making it the correct choice for reducing DynamoDB query latency in a serverless application.
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 a fully managed, highly available, in-memory cache for DynamoDB that delivers up to 10x read performance improvement by reducing response times from milliseconds to microseconds for repeated read queries. By integrating DAX with the Lambda function, the developer can cache the results of frequent DynamoDB queries directly in memory, bypassing the read capacity units and the underlying storage engine, which directly addresses the latency bottleneck shown in the X-Ray trace.
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
DynamoDB Accelerator (DAX) is a fully managed, in-memory cache specifically designed to sit in front of DynamoDB tables. It provides microsecond response times for read-heavy workloads by caching frequently accessed data, significantly improving performance for serverless applications. DAX is API-compatible with DynamoDB, requiring minimal application code changes to integrate and benefit from its high-performance caching capabilities, making it ideal for reducing read latency.
- ✗
Amazon ElastiCache for Redis
Why it's wrong here
Amazon ElastiCache for Redis is a general-purpose, in-memory data store that can be used for caching, but it lacks the native integration with DynamoDB that DAX offers. Implementing ElastiCache for DynamoDB caching requires custom application logic for cache invalidation, data serialization, and managing the caching layer, adding significant operational overhead. This approach increases development complexity and is not as optimized for reducing DynamoDB read latency as a purpose-built solution like DAX.
- ✗
DynamoDB Global Tables
Why it's wrong here
DynamoDB Global Tables are designed for multi-region, active-active replication, enabling globally distributed applications to provide low-latency data access to users worldwide and enhance disaster recovery. While they offer low-latency reads by serving data from the nearest replica, they do not function as a caching layer for repeated reads within a *single* AWS region. Their primary purpose is data availability and geographic distribution, not accelerating read performance for a specific table in one region through caching.
- ✗
DynamoDB Streams
Why it's wrong here
DynamoDB Streams provide a time-ordered sequence of item-level modifications (inserts, updates, and deletes) to a DynamoDB table, enabling event-driven architectures and real-time data processing. This feature is primarily used for change data capture (CDC), triggering Lambda functions, or replicating data to other services. DynamoDB Streams do not cache data or directly reduce read latency for client applications; their function is to capture and propagate data changes, not to accelerate read operations.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.