- A
The Lambda function does not have the required VPC permissions to access the RDS instance.
Why wrong: Lambda in a VPC can access RDS via the VPC without extra permissions; the issue is with SQS access.
- B
The VPC does not have a NAT gateway, so the Lambda function cannot poll the SQS queue.
Lambda in a VPC needs a NAT gateway to access public endpoints like SQS; without it, SQS polling fails, causing timeouts.
- C
The Lambda function timeout should be increased to accommodate database query time.
Why wrong: The query time is 2 seconds, which is within the 3-second timeout; the issue is network connectivity to SQS.
- D
The RDS instance is under-provisioned and causing slow queries.
Why wrong: The query time is 2 seconds, which is acceptable; the timeouts are due to SQS polling failure.
Quick Answer
The answer is that the VPC lacks a NAT gateway, preventing the Lambda function from polling the SQS queue. Lambda functions running inside a VPC lose default internet access, so they cannot reach the SQS API endpoint, which resides outside the VPC. Without a NAT gateway or VPC endpoints for SQS, the function’s polling requests time out, even though the database queries to RDS within the VPC complete successfully in about two seconds. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how VPC networking affects Lambda’s ability to interact with AWS services—a common trap is assuming that Lambda inside a VPC can freely access all AWS APIs, when in fact it requires explicit routing. Remember that Lambda in a VPC is like a private server: it can talk to neighbors (RDS) but needs a gateway to call home (SQS). A useful memory tip is “VPC Lambda needs a NAT to chat with SQS.”
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 company uses AWS Lambda functions within a VPC to process data from an Amazon SQS queue. The Lambda functions frequently timeout with the error 'Task timed out after 3.00 seconds'. The functions perform database operations on an RDS instance in the same VPC. The average database query takes 2 seconds. What is the MOST likely cause of the timeouts?
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 VPC does not have a NAT gateway, so the Lambda function cannot poll the SQS queue.
Option D is correct because Lambda functions in a VPC require a NAT gateway or VPC endpoints to access the SQS API, which is outside the VPC. Without a NAT gateway, the function cannot poll the SQS queue, causing timeouts. Option A is wrong because Lambda can access RDS within the same VPC without issues. Option B is wrong because 3-second timeout should be sufficient for a 2-second query if network is fine. Option C is wrong because the RDS instance size does not affect network connectivity to SQS.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 does not have the required VPC permissions to access the RDS instance.
Why it's wrong here
Lambda in a VPC can access RDS via the VPC without extra permissions; the issue is with SQS access.
- ✓
The VPC does not have a NAT gateway, so the Lambda function cannot poll the SQS queue.
- ✗
The Lambda function timeout should be increased to accommodate database query time.
Why it's wrong here
The query time is 2 seconds, which is within the 3-second timeout; the issue is network connectivity to SQS.
- ✗
The RDS instance is under-provisioned and causing slow queries.
Why it's wrong here
The query time is 2 seconds, which is acceptable; the timeouts are due to SQS polling failure.
Common exam traps
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.
Detailed technical explanation
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.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SAP-C02 NAT questions on configuration and troubleshooting.
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Continuous Improvement for Existing Solutions — study guide chapter
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FAQ
Questions learners often ask
What does this SAP-C02 question test?
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The VPC does not have a NAT gateway, so the Lambda function cannot poll the SQS queue. — Option D is correct because Lambda functions in a VPC require a NAT gateway or VPC endpoints to access the SQS API, which is outside the VPC. Without a NAT gateway, the function cannot poll the SQS queue, causing timeouts. Option A is wrong because Lambda can access RDS within the same VPC without issues. Option B is wrong because 3-second timeout should be sufficient for a 2-second query if network is fine. Option C is wrong because the RDS instance size does not affect network connectivity to SQS.
What should I do if I get this SAP-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SAP-C02 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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Same concept, more angles
1 more ways this is tested on SAP-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company runs a production AWS Lambda function that processes orders. Recently, the function has been timing out occasionally. The function uses a VPC with a single private subnet and has a timeout of 30 seconds. What is the MOST likely cause of the timeout?
medium- A.The function is experiencing cold starts due to high concurrency.
- B.The function is hitting the maximum concurrent execution limit.
- C.The function needs to be attached to a public subnet.
- ✓ D.The function does not have a NAT gateway or VPC endpoints to access external resources.
Why D: Option A is correct because Lambda functions in a VPC require a NAT gateway or VPC endpoints to access external services; without it, they cannot reach the internet, causing timeouts. Option C is wrong because Lambda automatically scales. Option D is wrong because the function already has a VPC configuration. Option B is wrong because concurrent executions do not cause timeouts.
Last reviewed: Jun 20, 2026
This SAP-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 SAP-C02 exam.
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