A developer is implementing Key Vault certificate retrieval. The application runs on Azure App Service and must avoid stored credentials. Which design should be used? The design must avoid adding custom operational scripts.
Managed identity lets Azure-hosted apps authenticate without stored secrets.
Why this answer
Managed identity (system-assigned or user-assigned) allows the App Service to authenticate to Key Vault without any stored credentials, because Azure automatically rotates the identity's service principal and provides an access token via the Azure Instance Metadata Service (IMDS) endpoint. By granting least-privilege access (e.g., a Key Vault access policy with only 'Get' on secrets), the design meets the requirement to avoid stored credentials and custom operational scripts.
Exam trap
The trap here is that candidates may think storing a client secret in Azure App Service application settings (Option B) is acceptable because it's not in source control, but the question explicitly requires avoiding stored credentials entirely, and managed identity is the only zero-credential solution.
How to eliminate wrong answers
Option A is wrong because using a shared administrator account requires storing credentials (username/password or certificate) in the application configuration or code, violating the 'avoid stored credentials' requirement. Option B is wrong because storing a client secret in source control is a security anti-pattern that exposes credentials in the codebase, and it still requires manual secret rotation and management. Option D is wrong because disabling authentication for the target resource (Key Vault) would allow anonymous access, which is a severe security vulnerability and contradicts the principle of least privilege.