Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For DVA-C02 candidates, the confusion often lies in distinguishing between different ways to reduce Lambda cold start latency. In production, it’s about knowing exactly how to optimize function initialization time without impacting scalability or cost. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
Zenix Solutions has developed a REST API using Amazon API Gateway that invokes a single AWS Lambda function. This Lambda serves multiple clients simultaneously but is only invoked sporadically. Although the Lambda’s code is well-optimized at runtime, users notice initial call delays due to cold starts. The development team wants to reduce the Lambda startup latency to improve user experience.
The Requirement: #
Identify the best developer-controlled option to minimize Lambda cold start delays while maintaining scalability.
The Options #
- A) Enable caching for the API Gateway REST API.
- B) Configure provisioned concurrency for the Lambda function.
- C) Use Lambda proxy integration for the REST API.
- D) Configure AWS Global Accelerator for the Lambda function.
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Correct Answer #
B
Quick Insight: The DVA-C02 Imperative #
To optimize Lambda cold start time, provisioned concurrency is the key option, allowing pre-warmed instances to serve requests immediately.
Enabling API Gateway caching benefits mostly response payloads, not cold start.
Lambda proxy integration impacts request routing but not cold start latency.
Global Accelerator improves network routing but does not affect Lambda initialization.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option B
The Winning Logic #
Provisioned concurrency keeps a specified number of Lambda instances initialized and ready to respond immediately, eliminating cold start delays. This is a developer-configured concurrency model designed specifically to address startup latency issues that occur with intermittent invocations or bursty traffic patterns.
- The developer can specify how many concurrent executions should be pre-warmed.
- Helps maintain consistent low-latency responses despite sporadic usage.
- Works seamlessly with API Gateway invoking Lambda functions.
The Trap (Distractor Analysis): #
- Why not A? API Gateway caching only caches endpoint responses, reducing backend compute calls but does not affect Lambda cold start latency.
- Why not C? Lambda proxy integration controls how API Gateway passes requests but doesn’t influence Lambda function startup or concurrency.
- Why not D? AWS Global Accelerator optimizes network routing for endpoints but does not reduce Lambda initialization time.
The Technical Blueprint #
# Example CLI to configure provisioned concurrency for your Lambda function version:
aws lambda put-provisioned-concurrency-config \
--function-name MyLambdaFunction \
--qualifier 1 \
--provisioned-concurrent-executions 5
This command pre-allocates 5 Lambda instances ready to serve requests immediately.
The Comparative Analysis #
| Option | API Complexity | Performance Impact | Use Case |
|---|---|---|---|
| A | Low | Caches response, no effect on cold starts | Useful for improving response speed when backend latency is high |
| B | Moderate - requires versioning and configuration | Eliminates cold start latency by pre-warming environments | Best for functions with sporadic traffic requiring low latency |
| C | Low | No impact on cold start | Controls request/response passing style |
| D | Moderate - networking setup | Improves network latency but not cold start time | Best for multi-region endpoint acceleration |
Real-World Application (Practitioner Insight) #
Exam Rule #
For the exam, always pick Provisioned Concurrency when asked about reducing Lambda cold start latency.
Real World #
In many projects, teams combine provisioned concurrency with autoscaling event-driven mechanisms to balance cost and performance, especially for unpredictable or spiky Lambda workloads.
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the DVA-C02 exam.