DVA-C02 Development with AWS Services Practice Question
A company uses Amazon DynamoDB as a session store for a web application. The application recently experienced a spike in traffic, causing increased read latency. The DynamoDB table has a read capacity of 5000 RCUs and uses eventual consistent reads. The application performs many GetItem calls. What should a developer do to improve read performance with minimal cost?
⚠ Common exam trap
Test-takers frequently assume increasing provisioned capacity (Option B) is the only way to handle read spikes, overlooking the cost and performance benefits of a caching layer like DAX for read-heavy workloads.
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
✓
Enable DynamoDB Accelerator (DAX) for the table
DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency for GetItem calls from single-digit milliseconds to microseconds. Since the application uses eventual consistent reads and performs many GetItem operations, DAX offloads reads from the table, improving performance without increasing provisioned RCUs. This is the most cost-effective solution because it avoids scaling the table's read capacity and only charges for the cache nodes used.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable DynamoDB Accelerator (DAX) for the table
Why this is correct
DynamoDB Accelerator (DAX) is a fully managed, highly available, in-memory cache specifically designed to reduce read latency for DynamoDB tables. By caching frequently accessed session data, DAX can serve requests with microsecond response times, significantly improving the performance of read-heavy applications like web session stores. This offloads read traffic from the underlying DynamoDB table, optimizing both latency and cost efficiency by minimizing direct DynamoDB calls.
- ✗
Increase the read capacity to 10000 RCUs
Why it's wrong here
Increasing the read capacity units (RCUs) for a DynamoDB table primarily addresses throttling issues by providing more throughput for concurrent read operations. However, it does not inherently reduce the individual request latency for each read, as the data still needs to be retrieved from the underlying storage. For a web session store experiencing high read latency, simply increasing RCUs would incur higher costs without directly solving the fundamental latency problem that caching mechanisms are designed to address.
- ✗
Configure DynamoDB global tables for the application
Why it's wrong here
Configuring DynamoDB global tables enables multi-region, active-active replication, allowing applications to read and write data in multiple AWS regions with eventual consistency. While global tables can improve disaster recovery and provide low-latency access to data for users geographically distributed across regions, they do not function as a local in-memory cache to reduce read latency within a single region for a specific application. This solution is focused on global data distribution and resilience, not on accelerating single-region read performance.
- ✗
Enable DynamoDB Streams and process updates asynchronously
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 real-time processing of changes. This feature is primarily used for triggering AWS Lambda functions, replicating data to other services, or building real-time analytics, rather than serving as a read cache for the primary application. Enabling streams would capture data changes but would not directly reduce the read latency experienced by the web application trying to retrieve session data.
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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.