The answer is to create an IAM role with the necessary permissions and assign it to the Lambda function as the execution role. This is correct because Lambda functions run within the AWS service environment and cannot use long-term access keys; instead, they rely on an IAM role that includes a trust policy allowing the Lambda service to assume it, and a permissions policy granting read-only access to the specific S3 bucket. The AWS Security Token Service (STS) then provides temporary credentials to the function at runtime, ensuring secure, scoped access. On the AWS Certified Developer Associate DVA-C02 exam, this concept tests your understanding of least-privilege permissions and the separation of roles from users—a common trap is confusing an IAM user or inline policy with the execution role, which is the only valid entity for granting service-level permissions. Remember the mnemonic: “Lambda Loves Roles, Not Users” to avoid selecting incorrect options like attaching policies directly to the function or using an IAM user.
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 needs to grant a Lambda function read-only access to an S3 bucket. Which IAM entity should be used to attach the permissions?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an IAM role with the necessary permissions and assign it to the Lambda function as the execution role.
Option D is correct because Lambda functions require an IAM role (execution role) to obtain temporary AWS credentials via the AWS Security Token Service (STS). This role must have a trust policy allowing Lambda to assume it, and an attached permissions policy granting read-only access to the S3 bucket. This is the standard and secure method for granting permissions to an AWS service like Lambda.
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.
✗
Create an IAM user and provide the credentials to the Lambda function.
Why it's wrong here
Lambda uses roles, not IAM users, for temporary credentials.
✗
Attach a resource-based policy to the S3 bucket.
Why it's wrong here
Resource-based policies allow cross-account access but are not the primary way to grant Lambda access.
✗
Attach a policy to an IAM group and add the Lambda function to the group.
Why it's wrong here
Lambda functions cannot be added to IAM groups.
✓
Create an IAM role with the necessary permissions and assign it to the Lambda function as the execution role.
Why this is correct
Lambda execution roles are IAM roles that grant permissions to the function.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse resource-based policies (which grant access to the principal specified in the policy) with identity-based policies (which grant permissions to the principal the policy is attached to), and incorrectly think a bucket policy alone can grant permissions to a Lambda function without an execution role.
Detailed technical explanation
How to think about this question
Under the hood, when a Lambda function is invoked, the Lambda service assumes the execution role using the `sts:AssumeRole` API call, receiving temporary security credentials that are then used for all subsequent AWS API calls. The trust policy of the role must explicitly allow the `lambda.amazonaws.com` service principal to assume it. A common real-world scenario is granting read-only access to a specific S3 bucket prefix (e.g., `arn:aws:s3:::my-bucket/data/*`) to limit the blast radius of compromised code.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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: Create an IAM role with the necessary permissions and assign it to the Lambda function as the execution role. — Option D is correct because Lambda functions require an IAM role (execution role) to obtain temporary AWS credentials via the AWS Security Token Service (STS). This role must have a trust policy allowing Lambda to assume it, and an attached permissions policy granting read-only access to the S3 bucket. This is the standard and secure method for granting permissions to an AWS service like Lambda.
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.