The answer is that the API request is missing the Authorization header containing the token, and the developer must add the ID token to that header. This is correct because the API Gateway Cognito authorizer specifically inspects the incoming HTTP request for a valid token in the Authorization header; if that header is absent or the token is placed elsewhere—such as in a custom header or query parameter—the authorizer immediately rejects the request with a 401 Unauthorized error, even if the user is authenticated in the user pool. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of how API Gateway authorizers enforce token placement, and it is a common trap to assume the token can be sent in any header or as a query string. A useful memory tip is: "Auth header or 401—Cognito checks the header, not the payload."
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A developer is building a mobile application that uses Amazon Cognito User Pools for authentication. The app needs to access a REST API hosted on AWS. The developer wants to use Cognito to authorize API requests. The API Gateway is configured with a Cognito User Pool authorizer. However, when testing, the API returns a 401 Unauthorized error even though the user is authenticated. The developer verified that the user exists in the user pool and the ID token is valid. What is the MOST likely cause and solution?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The API request is missing the Authorization header with the token. The developer should add the token to the Authorization header.
Option A is correct because the API Gateway authorizer expects an Authorization header with the token, and if the token is missing or in the wrong header, it returns 401. Option B is wrong because the method request header is not needed. Option C is wrong because the token should be the ID token, not access token. Option D is wrong because the Authorizer is already configured.
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.
✗
The API Gateway authorizer is not properly configured. The developer should delete and recreate the authorizer.
Why it's wrong here
The authorizer is configured; the issue is the missing header.
✗
The developer is using the wrong token. The API Gateway authorizer requires the access token, not the ID token.
Why it's wrong here
Cognito User Pool authorizer uses ID token.
✓
The API request is missing the Authorization header with the token. The developer should add the token to the Authorization header.
Why this is correct
API Gateway expects the token in the Authorization header by default.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Authentication checks who the user is.
✗
The API Gateway method request header is not mapped. The developer should add a mapping template to pass the token.
Why it's wrong here
Mapping templates are for data transformation, not for passing the token.
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.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related DVA-C02 questions on access control and AAA configuration.
Security — This question tests Security — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: The API request is missing the Authorization header with the token. The developer should add the token to the Authorization header. — Option A is correct because the API Gateway authorizer expects an Authorization header with the token, and if the token is missing or in the wrong header, it returns 401. Option B is wrong because the method request header is not needed. Option C is wrong because the token should be the ID token, not access token. Option D is wrong because the Authorizer is already configured.
What should I do if I get this DVA-C02 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 DVA-C02 questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Authentication checks who the user is.
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