SC-100 Practice Question: Design security solutions for applications and data
Your organization is deploying a new line-of-business application on Azure App Service. The app must authenticate users from Microsoft Entra ID and also access a downstream API that requires a client secret. You need to recommend the most secure method for managing the client secret. What should you use?
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
✓
Store the secret in Azure Key Vault and use a Key Vault reference in App Service.
Azure Key Vault provides secure storage for secrets and certificates, and App Service can reference them via managed identity or Key Vault references. Option A is wrong because the Azure AD app registration manifest is for application configuration and should not be used to store secrets; instead, use the 'Certificates & secrets' section. Option B is wrong because App Service application settings are less secure and can be accessed through the portal, lacking the fine-grained access control and auditing of Key Vault. Option D is wrong because storing the secret in code exposes it to source control and accidental disclosure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Store the secret in the Azure AD app registration manifest.
Why it's wrong here
Storing the secret in the Azure AD app registration manifest is insecure because the manifest is a configuration file that can be exported or exposed, and it does not provide the same security controls as a dedicated secret store.
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Store the secret in an App Service application setting.
Why it's wrong here
App Service application settings are stored in plain text within the Azure environment and can be accessed through the portal, APIs, or configuration management tools, making them less secure than using Key Vault with managed identity.
- ✓
Store the secret in Azure Key Vault and use a Key Vault reference in App Service.
Why this is correct
Correct. Azure Key Vault provides secure, centralized storage for secrets with encryption and access auditing. App Service can reference Key Vault secrets via Key Vault references, using a managed identity to authenticate without exposing the secret.
- ✗
Store the secret in the application code as a constant.
Why it's wrong here
Hard-coding a secret as a constant is insecure because the plaintext value becomes part of the source code and compiled binary. It can be exposed through source control history, decompilation, debug dumps, or logging, and it persists on disk in deployment artifacts. Any code review, leak of a repo, or compromise of a build pipeline immediately reveals the secret, and rotating it requires a full application redeployment rather than a centralized update.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SC-100 practice question is part of Courseiva's free Microsoft 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 SC-100 exam.