- A
AWS Security Token Service (STS)
STS issues temporary credentials.
- B
Amazon Cognito
Provides temporary credentials via identity pools.
- C
Amazon S3 Transfer Acceleration
Why wrong: Accelerates uploads but does not provide credentials.
- D
AWS Identity and Access Management (IAM)
Why wrong: IAM is for long-term users, not temporary credentials.
- E
AWS Key Management Service (KMS)
Why wrong: KMS manages encryption keys.
Question 524 of 1,616
Secure S3 Uploads from Mobile Apps Using STS and Amazon Cognito
This DVA-C02 practice question tests your understanding of development with aws services. 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 is designing a mobile application that needs to upload files to Amazon S3. The developer wants to use temporary credentials to avoid storing long-term AWS credentials on the device. Which TWO services should the developer use together?
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
✓
AWS Security Token Service (STS)
AWS Security Token Service (STS) is used to generate temporary, limited-privilege credentials for accessing AWS resources, such as S3 buckets. Amazon Cognito provides identity pools that can automatically obtain and refresh STS tokens for authenticated users, eliminating the need to store long-term AWS credentials on the mobile device. Together, they enable secure, temporary credential management for file uploads.
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.
- ✓
AWS Security Token Service (STS)
Why this is correct
STS issues temporary credentials.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Amazon Cognito
Why this is correct
Provides temporary credentials via identity pools.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Amazon S3 Transfer Acceleration
Why it's wrong here
Accelerates uploads but does not provide credentials.
- ✗
AWS Identity and Access Management (IAM)
Why it's wrong here
IAM is for long-term users, not temporary credentials.
- ✗
AWS Key Management Service (KMS)
Why it's wrong here
KMS manages encryption keys.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse IAM (which manages long-term credentials) with STS (which issues temporary credentials), or they mistakenly think S3 Transfer Acceleration or KMS can handle authentication, when in fact only STS and Cognito together solve the temporary credential requirement for mobile apps.
Detailed technical explanation
How to think about this question
Under the hood, Amazon Cognito identity pools integrate with AWS STS via the GetId and GetCredentialsForIdentity API calls, which return an access key, secret key, and session token with a configurable expiration (default 1 hour, max 12 hours). The mobile app can then sign S3 PUT requests using these temporary credentials, which are automatically scoped to the permissions defined in the IAM role associated with the identity pool. This pattern is critical for scenarios like a photo-sharing app where thousands of devices upload files without exposing permanent keys.
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?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: AWS Security Token Service (STS) — AWS Security Token Service (STS) is used to generate temporary, limited-privilege credentials for accessing AWS resources, such as S3 buckets. Amazon Cognito provides identity pools that can automatically obtain and refresh STS tokens for authenticated users, eliminating the need to store long-term AWS credentials on the mobile device. Together, they enable secure, temporary credential management for file uploads.
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.
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Last reviewed: Jul 4, 2026
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.
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