Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For AWS DVA-C02 candidates, the confusion often lies in understanding ephemeral credential expiration in federated CLI access. In production, this is about knowing exactly how IAM Identity Center tokens interact with AWS CLI cached sessions and reauthentication needs. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
CloudTech Solutions has integrated AWS IAM Identity Center (formerly AWS SSO) for developers to securely access AWS APIs through the AWS CLI and SDKs on their laptops. Initially, API calls worked seamlessly right after the SSO login. Recently, one developer started receiving “Access Denied” errors when running the same scripts and CLI commands—without any changes made to local configuration files or deployment scripts. The developer suspects an issue with authentication or permissions.
The Requirement: #
Determine the MOST likely reason the developer’s CLI and SDK API calls are now failing with access denied errors after previously working fine with IAM Identity Center.
The Options #
- A) The access permissions on the developer’s local AWS CLI binary have been altered.
- B) The permission set linked to IAM Identity Center roles lacks the necessary permissions for the API calls.
- C) The IAM Identity Center federated credentials or access tokens have expired and need refreshing.
- D) The developer is mistakenly targeting an incorrect AWS account environment.
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Correct Answer #
C
Quick Insight: The Developer Access Token Expiry Imperative #
- IAM Identity Center issues short-lived credentials that expire and require the user to re-authenticate via
aws sso login.- Unlike static access keys, these tokens do not persist indefinitely and lead to “Access Denied” if the cached session expires.
- This concept is critical for developers using SSO-based access with the AWS CLI or SDKs to understand session lifecycle and token refresh mechanics.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option C
The Winning Logic #
IAM Identity Center leverages temporary federated credentials obtained during an SSO login flow. These access tokens are automatically cached on the developer’s machine but are short-lived (typically 1 hour by default, configurable up to 12 hours). Once expired, API calls using stale cached credentials fail with “Access Denied” until the user runs aws sso login again to refresh tokens.
- This expiration is independent of any changes to CLI binaries or local config.
- The permission set attached to IAM Identity Center roles does not change unless altered by administrators.
- Typically, targeting the wrong account would produce different error patterns or no access at all, but here the symptom is related to expired authentication sessions.
The Trap (Distractor Analysis): #
-
Why not A?
The AWS CLI binary permissions rarely change spontaneously and would rather cause “Command not found” or OS-level errors, not AWS “Access Denied”. -
Why not B?
If the permission set was inadequate, problems would have existed consistently rather than suddenly after initially working. -
Why not D?
Accessing the wrong AWS account would likely fail immediately or show different account-specific resource errors, and this scenario emphasizes no configuration changes.
The Technical Blueprint #
# Common fix for expired IAM Identity Center tokens:
aws sso login --profile your-profile-name
# This command refreshes the federated credentials enabling subsequent CLI/SDK calls to succeed
The Comparative Analysis #
| Option | API Complexity | Performance Impact | Use Case |
|---|---|---|---|
| A | None | CLI invocation fails | Unlikely in this scenario |
| B | Medium | Persistent failures | Permissions misconfigured |
| C | Low | Temporary failure | Typical token expiry behavior (correct) |
| D | Low | Misrouted calls | Would cause other error types |
Real-World Application (Practitioner Insight) #
Exam Rule #
“For the exam, always pick token/session expiry when you see previously working IAM Identity Center access suddenly break without config changes.”
Real World #
“In reality, developers often miss running aws sso login periodically or setting session duration appropriately, leading to avoidable production disruptions.”
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the AWS DVA-C02 exam.