- A
The Lambda function is not configured with enough memory
Why wrong: Memory affects CPU but not network connectivity.
- B
The Lambda function is not using a reserved concurrency limit
Why wrong: Reserved concurrency limits scaling, not connectivity.
- C
The Lambda function is not attached to the same VPC as the RDS instance
Lambda must be in the same VPC or use VPC peering to access RDS.
- D
The Lambda function's execution role lacks RDS permissions
Why wrong: Permissions affect API calls, not TCP connections.
Question 1,381 of 1,616
Lambda RDS Timeout Cause
This DVA-C02 practice question tests your understanding of development with aws services. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 using AWS Lambda with an Amazon RDS MySQL database. The Lambda function frequently times out when connecting to the database. What is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
✓
The Lambda function is not attached to the same VPC as the RDS instance
Option C is correct because Lambda functions must be attached to the same VPC as the RDS instance to connect via a private IP address. Without VPC attachment, the Lambda function attempts to connect over the public internet, which can cause timeouts due to network latency, security group restrictions, or the RDS instance being configured as publicly inaccessible.
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.
- ✗
The Lambda function is not configured with enough memory
Why it's wrong here
Memory affects CPU but not network connectivity.
- ✗
The Lambda function is not using a reserved concurrency limit
Why it's wrong here
Reserved concurrency limits scaling, not connectivity.
- ✓
The Lambda function is not attached to the same VPC as the RDS instance
Why this is correct
Lambda must be in the same VPC or use VPC peering to access RDS.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The Lambda function's execution role lacks RDS permissions
Why it's wrong here
Permissions affect API calls, not TCP connections.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume timeout issues are due to insufficient memory or IAM permissions, but the real cause is almost always a network connectivity problem when Lambda cannot reach the RDS instance inside a VPC.
Detailed technical explanation
How to think about this question
Lambda functions run in a managed VPC by default, but to access resources in a customer VPC (like RDS), the function must be configured with VPC settings that include subnets and security groups. The security group attached to the Lambda function must allow outbound traffic to the RDS security group on port 3306 (MySQL), and the RDS security group must allow inbound traffic from the Lambda security group. Without this configuration, the Lambda function cannot establish a TCP connection, leading to timeouts after the default 3-second timeout for idle connections.
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.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Development with AWS Services — study guide chapter
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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: The Lambda function is not attached to the same VPC as the RDS instance — Option C is correct because Lambda functions must be attached to the same VPC as the RDS instance to connect via a private IP address. Without VPC attachment, the Lambda function attempts to connect over the public internet, which can cause timeouts due to network latency, security group restrictions, or the RDS instance being configured as publicly inaccessible.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
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.
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