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Security →mediumMultiple ChoiceObjective-mapped

How to Securely Grant EC2 Access to S3 Using an IAM Role

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.

An application running on EC2 needs to access an S3 bucket. The security team wants to avoid using long-term access keys. What is the most secure approach?

A
Generate an access key and secret key for an IAM user and store them on the instance.
Why wrong: Long-term keys are less secure.
B
Create a new IAM user and store the credentials in S3 with bucket policies.
Why wrong: Long-term keys are still used.
C
Use AWS Systems Manager Parameter Store to store the credentials and retrieve them at runtime.
Why wrong: Still uses long-term keys stored in Parameter Store.
D
Launch the EC2 instance with an IAM role that grants S3 access.
Temporary credentials are automatically rotated.

Full breakdown with real-world context →

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

✓

Launch the EC2 instance with an IAM role that grants S3 access.

Option D is correct because assigning an IAM role to an EC2 instance allows the instance to obtain temporary security credentials from the AWS Security Token Service (STS) automatically via the instance metadata service. This eliminates the need to store, rotate, or manage long-term access keys, adhering to the security team's requirement for a credential-less approach. The IAM role's permissions policy grants the EC2 instance access to the S3 bucket, and the credentials are automatically rotated by AWS before they expire.

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.

✗
Generate an access key and secret key for an IAM user and store them on the instance.
Why it's wrong here
Long-term keys are less secure.
✗
Create a new IAM user and store the credentials in S3 with bucket policies.
Why it's wrong here
Long-term keys are still used.
✗
Use AWS Systems Manager Parameter Store to store the credentials and retrieve them at runtime.
Why it's wrong here
Still uses long-term keys stored in Parameter Store.
✓
Launch the EC2 instance with an IAM role that grants S3 access.
Why this is correct
Temporary credentials are automatically rotated.
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 often confuse 'secure storage' (like Parameter Store or Secrets Manager) with 'no long-term credentials at all,' failing to recognize that an IAM role provides temporary credentials that are inherently more secure and require no key management on the instance.

Detailed technical explanation

How to think about this question

When an EC2 instance is launched with an IAM role, the AWS credential provider chain automatically retrieves temporary credentials from the instance metadata service (IMDS) at http://169.254.169.254/latest/meta-data/iam/security-credentials/. These credentials are signed with a 6-hour expiration by default and are automatically refreshed by the AWS SDKs, ensuring continuous access without manual rotation. In real-world scenarios, this approach also simplifies auditing because all API calls made by the instance are logged in AWS CloudTrail with the role's session context, enabling precise tracking of actions.

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.

Quick reference

AWS S3 Storage Class Comparison

Storage Class	Min Duration	Retrieval	Use Case
S3 Standard	None	Immediate	Frequently accessed data
S3 Standard-IA	30 days	Immediate	Infrequent access, rapid retrieval
S3 One Zone-IA	30 days	Immediate	Non-critical infrequent data
S3 Intelligent-Tiering	None	Immediate–hours	Unknown or changing access patterns
S3 Glacier Instant	90 days	Milliseconds	Archive with instant retrieval
S3 Glacier Flexible	90 days	Minutes–hours	Archive, flexible retrieval
S3 Glacier Deep Archive	180 days	Hours	Long-term compliance archive

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this DVA-C02 question test?

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: Launch the EC2 instance with an IAM role that grants S3 access. — Option D is correct because assigning an IAM role to an EC2 instance allows the instance to obtain temporary security credentials from the AWS Security Token Service (STS) automatically via the instance metadata service. This eliminates the need to store, rotate, or manage long-term access keys, adhering to the security team's requirement for a credential-less approach. The IAM role's permissions policy grants the EC2 instance access to the S3 bucket, and the credentials are automatically rotated by AWS before they expire.

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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Same concept, more angles

1 more ways this is tested on DVA-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. An application running on EC2 needs to access an S3 bucket. What is the most secure way to grant access?

easy

A.Generate an IAM user access key and store it in a file on the instance
B.Use pre-signed URLs for each request
C.Make the S3 bucket public
✓ D.Create an IAM role with S3 permissions and attach it to the EC2 instance

Why D: Using an IAM role attached to the EC2 instance is the most secure because it provides temporary credentials and avoids hardcoding keys. Option A (IAM user access key stored on the instance) is less secure as it exposes long-term credentials. Option B (pre-signed URLs) is not suitable for ongoing access due to short expiration. Option C (making the S3 bucket public) is insecure as it allows anyone to access the bucket.

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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.