The missing configuration is a VPC endpoint for CloudWatch Logs, because when a Lambda function is attached to a VPC, it loses default internet connectivity and cannot reach the public CloudWatch Logs API endpoints, even if its execution role has the correct logging permissions. Without a VPC endpoint (com.amazonaws.region.logs) or a NAT gateway, the network path is blocked, so the function’s log writes silently fail. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of how VPC isolation impacts Lambda’s outbound access—a common trap is assuming that IAM permissions alone are sufficient. Remember that VPC-attached Lambda functions require explicit network routes to AWS services; a NAT gateway or VPC endpoint is mandatory for CloudWatch Logs. Memory tip: “VPC blocks the path, so add an endpoint for the log bath.”
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. 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 developer is troubleshooting an issue where an AWS Lambda function cannot write logs to Amazon CloudWatch Logs. The Lambda function has an execution role with a policy that allows logs:CreateLogGroup, logs:CreateLogStream, and logs:PutLogEvents. Which additional configuration is likely missing?
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 in a VPC without a VPC endpoint for CloudWatch Logs.
Option C is correct because when a Lambda function is attached to a VPC, it loses default internet connectivity, including the ability to reach the CloudWatch Logs API endpoints. Even if the execution role grants the necessary permissions, the function cannot send logs unless a VPC endpoint for CloudWatch Logs (com.amazonaws.region.logs) is created in the VPC, or the function has a NATgateway to route traffic to the public endpoint.
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 CloudWatch Logs log group is encrypted with a customer-managed KMS key.
Why it's wrong here
If the log group uses a custom KMS key, the Lambda execution role needs kms:Decrypt permission, which is not listed.
✗
The log group name must start with '/aws/lambda/'.
Why it's wrong here
Lambda automatically uses the correct prefix.
✓
The Lambda function is in a VPC without a VPC endpoint for CloudWatch Logs.
Why this is correct
If the function is in a VPC, it needs either a NATgateway or a VPC endpoint to reach CloudWatch Logs.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Lambda function is not configured with a log group name.
Why it's wrong here
Lambda automatically uses a default log group name based on the function name.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume IAM permissions are the only requirement for CloudWatch Logs integration, overlooking the network connectivity constraints introduced by VPC attachment.
Detailed technical explanation
How to think about this question
When a Lambda function is deployed in a VPC, it uses an Elastic Network Interface (ENI) and routes all traffic through the VPC. Without a VPC endpoint for CloudWatch Logs (which uses AWS PrivateLink), the function cannot resolve or connect to the logs API endpoint (logs.region.amazonaws.com). A common real-world scenario is a Lambda function that processes data from an RDS database in a private subnet and fails silently because logs are not written, making debugging difficult.
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 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security — This question tests Security — 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 in a VPC without a VPC endpoint for CloudWatch Logs. — Option C is correct because when a Lambda function is attached to a VPC, it loses default internet connectivity, including the ability to reach the CloudWatch Logs API endpoints. Even if the execution role grants the necessary permissions, the function cannot send logs unless a VPC endpoint for CloudWatch Logs (com.amazonaws.region.logs) is created in the VPC, or the function has a NAT gateway to route traffic to the public endpoint.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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 Lambda function needs to write logs to CloudWatch Logs. The developer attaches an IAM role with a policy that allows logs:CreateLogGroup and logs:PutLogEvents. However, logs are not appearing. What is the most likely cause?
hard
A.The Lambda function is not configured to use a VPC.
B.The IAM role does not have a trust policy that allows Lambda to assume it.
✓ C.The IAM policy does not include logs:CreateLogStream.
D.The CloudWatch Logs log group does not exist.
Why C: Lambda requires the `logs:CreateLogStream` permission to create a log stream within a log group before it can write log events. Without this permission, the function can create the log group but cannot create the individual log stream needed to store log entries, causing logs to silently fail to appear.
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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.
Question Discussion
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