Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A developer is building a web application that uses Amazon DynamoDB as the database. The application needs to store user session data and must support eventual consistency reads for most use cases, but strongly consistent reads for critical operations. The developer wants to minimize costs. Which read capacity unit (RCU) configuration should the developer use?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Use on-demand capacity mode to pay per request, avoiding provisioned capacity costs.
On-demand mode is ideal for unpredictable traffic and eliminates the overhead of capacity planning, often resulting in lower costs for variable workloads like session data.
B
Distractor review
Use provisioned capacity with 1 RCU per item, since eventually consistent reads consume half the RCUs.
The RCU consumption depends on item size, not a fixed '1 RCU per item'. Eventual consistency reads use 0.5 RCU per 4KB item, but this option inaccurately describes the cost.
C
Distractor review
Use provisioned capacity with sufficient RCUs to handle strongly consistent reads, as they consume the same as eventually consistent.
Strongly consistent reads consume twice the RCUs of eventually consistent reads (1 RCU per 4KB item vs. 0.5 RCU).
D
Distractor review
Use provisioned capacity with enough RCUs for peak traffic, and use DynamoDB Accelerator (DAX) for caching.
Adding DAX incurs additional costs, making it more expensive. The goal is to minimize costs, so on-demand is a better option.
Common exam trap
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Technical deep dive
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Related practice questions
Related DVA-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A developer is building a REST API using Amazon API Gateway that will serve static content from an Amazon S3 bucket. The API should cache responses for frequently accessed objects to reduce latency. Which API Gateway feature should the developer enable?
Question 2
A developer is running a web application on multiple Amazon EC2 instances behind an Application Load Balancer (ALB). The application needs to store user session state that must be available across all instances. The session data is small and temporary but must survive individual instance failures. Which AWS service should the developer use to store this session state?
Question 3
A developer has an AWS Lambda function that processes messages from an Amazon SQS standard queue. The function is idempotent and currently has a batch size of 10. The developer wants to increase throughput and increases the batch size to 100. After the change, CloudWatch metrics show a significant increase in throttles and the queue backlog is growing. The function's reserved concurrency is set to 10. What is the most effective action to resolve the throttling and improve throughput?
Question 4
A developer is managing an application running on Amazon EC2 instances behind an Application Load Balancer. Users report that the application becomes unresponsive after several hours, and restarting the instance temporarily fixes the issue. The developer suspects a memory leak but cannot add custom instrumentation. Which AWS service can collect memory utilization metrics and help identify the memory leak with minimal configuration?
Question 5
A developer is building a serverless web application using AWS Lambda and Amazon DynamoDB. The application needs to perform complex aggregations on data stored in DynamoDB. Which AWS service should the developer use to perform these aggregations efficiently without reading all the data into Lambda?
Question 6
A developer has an Amazon S3 bucket containing private user documents. The application must generate a time-limited URL for users to download their own documents without requiring the users to have AWS credentials. Which solution should the developer use?
FAQ
Questions learners often ask
What does this DVA-C02 question test?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: Use on-demand capacity mode to pay per request, avoiding provisioned capacity costs. — On-demand capacity mode is the best choice for variable or unknown workloads, as it automatically scales and charges per request, avoiding the need to provision for peak traffic. It is cost-effective for session data that may have unpredictable traffic patterns. Option B is incorrect because eventually consistent reads consume half the RCUs of strongly consistent reads, but the statement '1 RCU per item' is misleading. Option C is incorrect because strongly consistent reads consume double the RCUs. Option D introduces DynamoDB Accelerator (DAX), which adds cost, contradicting the goal of minimizing costs.
What should I do if I get this DVA-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
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