- A
Hardcode the IAM user access keys in the application code
Why wrong: Hardcoded credentials are a critical security vulnerability — they can be exposed through code repositories, logs, or instance access, and are difficult to rotate.
- B
Store IAM access keys in environment variables on the EC2 instance
Why wrong: Environment variables on EC2 are accessible to all processes on the instance and can be exposed through process listings or application vulnerabilities.
- C
Attach an IAM role with the appropriate S3 permissions to the EC2 instance
IAM roles provide automatically rotated temporary credentials via instance metadata — no long-term keys to manage, no credentials to steal, and the minimal permissions pattern is enforced.
- D
Create an IAM user and configure the instance with its credentials
Why wrong: IAM user credentials stored on instances are long-term and require manual rotation — IAM roles are the secure, AWS-recommended alternative.
Quick Answer
The answer is to attach an IAM role with the appropriate S3 permissions to the EC2 instance. This is the most secure method because the role provides the instance with temporary, automatically rotated credentials via the Instance Metadata Service (IMDS), eliminating the need to hardcode or store long-term access keys on the instance. By granting only the required S3 write permissions through the role’s policy, you follow the principle of least privilege, which is a core security best practice. On the AWS Certified Cloud Practitioner CLF-C02 exam, this scenario tests your understanding of IAM roles versus access keys—a common trap is choosing to store keys directly on the instance, which is insecure and violates AWS best practices. Remember, roles are always preferred for granting EC2 permissions to other AWS services like S3. A helpful memory tip: “Roles rotate, keys stay—never put keys on the instance.”
CLF-C02 Security and Compliance Practice Question
This CLF-C02 practice question tests your understanding of security and compliance. 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 company needs to grant an EC2 instance permission to write to an S3 bucket. What is the most secure way to accomplish this?
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
Attach an IAM role with the appropriate S3 permissions to the EC2 instance
Option C is correct because attaching an IAM role to an EC2 instance allows the instance to securely obtain temporary credentials via the instance metadata service (IMDS). These credentials are automatically rotated by AWS, eliminating the need to hardcode or store long-term access keys. The role's policy grants only the necessary S3 write permissions, following the principle of least privilege.
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.
- ✗
Hardcode the IAM user access keys in the application code
Why it's wrong here
Hardcoded credentials are a critical security vulnerability — they can be exposed through code repositories, logs, or instance access, and are difficult to rotate.
- ✗
Store IAM access keys in environment variables on the EC2 instance
Why it's wrong here
Environment variables on EC2 are accessible to all processes on the instance and can be exposed through process listings or application vulnerabilities.
- ✓
Attach an IAM role with the appropriate S3 permissions to the EC2 instance
Why this is correct
IAM roles provide automatically rotated temporary credentials via instance metadata — no long-term keys to manage, no credentials to steal, and the minimal permissions pattern is enforced.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create an IAM user and configure the instance with its credentials
Why it's wrong here
IAM user credentials stored on instances are long-term and require manual rotation — IAM roles are the secure, AWS-recommended alternative.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think storing credentials in environment variables is secure because they are not in code, but AWS explicitly recommends IAM roles over any form of long-term access key storage for EC2 instances.
Detailed technical explanation
How to think about this question
When an IAM role is attached to an EC2 instance, the instance retrieves temporary security credentials from the instance metadata service (IMDS) at http://169.254.169.254/latest/meta-data/iam/security-credentials/. These credentials are valid for a configurable duration (default 6 hours) and are automatically refreshed by the AWS SDKs. This mechanism also supports IMDSv2, which requires session-oriented requests to mitigate SSRF vulnerabilities.
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.
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Security and Compliance — study guide chapter
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
Security and Compliance — This question tests Security and Compliance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Attach an IAM role with the appropriate S3 permissions to the EC2 instance — Option C is correct because attaching an IAM role to an EC2 instance allows the instance to securely obtain temporary credentials via the instance metadata service (IMDS). These credentials are automatically rotated by AWS, eliminating the need to hardcode or store long-term access keys. The role's policy grants only the necessary S3 write permissions, following the principle of least privilege.
What should I do if I get this CLF-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.
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Last reviewed: Jun 11, 2026
This CLF-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 CLF-C02 exam.
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