The answer is the OAuth 2.0 authorization code flow with PKCE. This flow is correct because it ensures the customer-facing web app can securely obtain an authorization code to exchange for tokens, while PKCE (Proof Key for Code Exchange) prevents interception attacks by requiring a dynamically generated code verifier and challenge, all without the application ever handling user passwords. On the Microsoft Cybersecurity Architect exam, this scenario tests your ability to distinguish between flows based on client type and security requirements—a common trap is choosing the implicit grant flow, which is deprecated, or the client credentials flow, which lacks user context. Remember that PKCE is mandatory for public clients like single-page and mobile apps, and it is now the recommended standard for any authorization code flow. A useful memory tip: "PKCE protects the public client's code from being intercepted, keeping the password out of the app's hands."
SC-100 Practice Question: Design security solutions for applications and data
This SC-100 practice question tests your understanding of design security solutions for applications and data. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Your organization is deploying a customer-facing web application in Azure. The application must authenticate users via Microsoft Entra ID and access Microsoft Graph to read user profiles. The security team requires that the application never has access to user passwords. Which authentication flow should you recommend?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
Why wrong: Implicit grant flow is deprecated because tokens are returned directly in the URL fragment, posing security risks.
B
OAuth 2.0 device authorization flow
Why wrong: Device authorization flow is designed for smart TVs or CLI tools, not a typical web application.
C
OAuth 2.0 client credentials grant flow
Why wrong: Client credentials flow is used for server-to-server authentication without a user present, so it cannot read user profiles on behalf of a signed-in user.
D
OAuth 2.0 authorization code flow with PKCE
This flow obtains an authorization code after user consent, then exchanges it for tokens. PKCE ensures the code cannot be intercepted. No password is exposed.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OAuth 2.0 authorization code flow with PKCE
Option B is correct because the OAuth 2.0 authorization code flow with PKCE is the recommended flow for native and web apps that need to access APIs without exposing user credentials. Option A is wrong because client credentials flow is for server-to-server scenarios without a user context. Option C is wrong because device authorization flow is for devices with limited input capabilities. Option D is wrong because implicit grant flow is deprecated due to security concerns.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
OAuth 2.0 implicit grant flow
Why it's wrong here
Implicit grant flow is deprecated because tokens are returned directly in the URL fragment, posing security risks.
✗
OAuth 2.0 device authorization flow
Why it's wrong here
Device authorization flow is designed for smart TVs or CLI tools, not a typical web application.
✗
OAuth 2.0 client credentials grant flow
Why it's wrong here
Client credentials flow is used for server-to-server authentication without a user present, so it cannot read user profiles on behalf of a signed-in user.
✓
OAuth 2.0 authorization code flow with PKCE
Why this is correct
This flow obtains an authorization code after user consent, then exchanges it for tokens. PKCE ensures the code cannot be intercepted. No password is exposed.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Authentication checks who the user is.
Common exam traps
Common exam trap: authentication is not authorization
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
How to think about this question
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.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-100 question in full detail.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related SC-100 questions on access control and AAA configuration.
Design security solutions for applications and data — This question tests Design security solutions for applications and data — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: OAuth 2.0 authorization code flow with PKCE — Option B is correct because the OAuth 2.0 authorization code flow with PKCE is the recommended flow for native and web apps that need to access APIs without exposing user credentials. Option A is wrong because client credentials flow is for server-to-server scenarios without a user context. Option C is wrong because device authorization flow is for devices with limited input capabilities. Option D is wrong because implicit grant flow is deprecated due to security concerns.
What should I do if I get this SC-100 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related SC-100 questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
What is the key concept behind this question?
Authentication checks who the user is.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Your company is deploying Microsoft Entra ID for application authentication. You need to register a new web application that uses OAuth 2.0 for user sign-in. Which authentication flow should you use?
easy
A.Device code flow
✓ B.Authorization code flow
C.Implicit flow
D.Client credentials flow
Why B: Option B is correct because Authorization Code Flow is the recommended flow for web applications that have a backend server. Option A is wrong because Implicit Flow is deprecated for user sign-in. Option C is wrong because Client Credentials Flow is for server-to-server without user. Option D is wrong because Device Code Flow is for input-constrained devices.
Variation 2. You need to design a secure solution for a web application that authenticates users via Microsoft Entra ID and calls a downstream API. Which TWO should you implement to secure the application? (Choose TWO.)
medium
✓ A.Use the OAuth 2.0 authorization code flow with PKCE.
✓ B.Store application secrets in Azure Key Vault.
C.Store application secrets in app configuration files.
D.Use the OAuth 2.0 client credentials flow.
E.Use shared access signatures (SAS) for API authentication.
Why A: B and C are correct. Using OAuth 2.0 authorization code flow (with PKCE) is the recommended authentication flow for web apps. Storing secrets in Azure Key Vault ensures they are securely managed. Option A is wrong because the client credentials flow is for server-to-server, not on behalf of users. Option D is wrong because storing secrets in configuration files is insecure. Option E is wrong because shared access signatures (SAS) are for storage, not API authentication.
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