Quick Answer
The answer is AWS STS (Security Token Service), which is the correct service for generating temporary credentials for an IAM user to access an S3 bucket for a limited duration. AWS STS works by issuing short-lived access keys and session tokens that grant precisely scoped permissions, allowing you to enforce a one-hour time limit without modifying the user’s permanent credentials. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of credential lifecycle management and the distinction between generating temporary credentials via STS versus assuming an IAM role, which is a common trap—roles provide temporary credentials but are assumed by a principal, not generated for a specific user. Another frequent distractor is Amazon Cognito, which handles identity federation for external users, not direct IAM user access. Remember the mnemonic: “STS gives the temporary keys, roles are for the assume-ease.”
This DOP-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 DevOps engineer needs to grant an IAM user temporary access to an S3 bucket for exactly one hour. Which AWS service should be used to generate temporary credentials?
Amazon Cognito
Why wrong: Cognito is for user identity pools and federation, not for generating temporary credentials for IAM users.
AWS SSO
Why wrong: SSO provides portal access but does not directly generate temporary credentials.
AWS STS
STS generates temporary credentials with a specified duration.
AWS IAM
Why wrong: IAM is used for permanent credentials, not temporary.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AWS STS
AWS STS (Security Token Service) is used to generate temporary, limited-privilege credentials for IAM users or federated users. IAM roles provide temporary credentials but are assumed, not generated for a specific user. Cognito is for identity federation with mobile/web apps. SSO provides single sign-on access.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Amazon Cognito
Why it's wrong here
Cognito is for user identity pools and federation, not for generating temporary credentials for IAM users.
AWS SSO
Why it's wrong here
SSO provides portal access but does not directly generate temporary credentials.
AWS STS
Why this is correct
STS generates temporary credentials with a specified duration.
Related concept
Authentication checks who the user is.
AWS IAM
Why it's wrong here
IAM is used for permanent credentials, not temporary.
Common exam traps
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
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
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related DOP-C02 questions on access control and AAA configuration.
Security and Compliance — study guide chapter
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FAQ
Security and Compliance — This question tests Security and Compliance — Authentication checks who the user is..
The correct answer is: AWS STS — AWS STS (Security Token Service) is used to generate temporary, limited-privilege credentials for IAM users or federated users. IAM roles provide temporary credentials but are assumed, not generated for a specific user. Cognito is for identity federation with mobile/web apps. SSO provides single sign-on access.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related DOP-C02 questions on access control and AAA configuration.
Authentication checks who the user is.
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Last reviewed: Jun 20, 2026
This DOP-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 DOP-C02 exam.
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