The correct answer is the OAuth 2.0 authorization code flow with PKCE (Proof Key for Code Exchange). This flow is the recommended standard for securing a web API called from a single-page application (SPA) using Microsoft Entra ID because it mitigates the security risks inherent in browser-based apps, specifically the inability to securely store a client secret. By requiring the SPA to generate a cryptographic code verifier and challenge during the authorization request, PKCE ensures that even if the authorization code is intercepted, it cannot be exchanged for tokens without the original verifier, effectively preventing authorization code interception attacks. On the Microsoft Azure Developer Associate AZ-204 exam, this scenario tests your understanding of modern authentication best practices for SPAs; a common trap is selecting the deprecated implicit flow, which exposes access tokens in the URL fragment and is no longer recommended by Microsoft. Remember the mnemonic “SPA needs PKCE” to instantly recall that single-page applications require the proof key extension for secure token acquisition.
AZ-204 Implement Azure security Practice Question
This AZ-204 practice question tests your understanding of implement azure security. 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.
You need to secure a web API that is called from a single-page application (SPA). The API uses Microsoft Entra ID for authentication. Which OAuth 2.0 flow should the SPA use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Authorization code flow with PKCE
The authorization code flow with PKCE is recommended for SPAs because it provides better security than implicit flow. Option A is wrong because client credentials flow is for server-to-server communication. Option B is wrong because implicit flow is deprecated. Option D is wrong because resource owner password credentials flow is not recommended for SPAs.
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.
✓
Authorization code flow with PKCE
Why this is correct
This flow is secure for SPAs as it uses a code exchange and PKCE to prevent interception.
Related concept
Authentication checks who the user is.
✗
Resource owner password credentials flow
Why it's wrong here
This flow requires user credentials and is not recommended for SPAs.
✗
Client credentials flow
Why it's wrong here
Client credentials flow is used for daemon applications, not SPAs.
✗
Implicit flow
Why it's wrong here
Implicit flow is deprecated and less secure than authorization code flow with PKCE.
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 AZ-204 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 AZ-204 questions on access control and AAA configuration.
Implement Azure security — This question tests Implement Azure security — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Authorization code flow with PKCE — The authorization code flow with PKCE is recommended for SPAs because it provides better security than implicit flow. Option A is wrong because client credentials flow is for server-to-server communication. Option B is wrong because implicit flow is deprecated. Option D is wrong because resource owner password credentials flow is not recommended for SPAs.
What should I do if I get this AZ-204 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 AZ-204 questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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