The answer is a JWT authorizer configured for the OpenID Connect issuer. This is correct because API Gateway’s JWT authorizer natively validates JSON Web Tokens issued by an external OpenID Connect provider, verifying the token’s signature, expiry, and issuer against the provider’s JWKS endpoint without requiring custom Lambda code. On the SAA-C03 exam, this scenario tests your understanding of when to use a managed authorizer versus a custom Lambda authorizer—a common trap is choosing a Lambda authorizer for OIDC tokens, which adds unnecessary complexity and cost. Remember that if your tokens are standards-based (JWT) and come from an external OIDC provider, the built-in JWT authorizer is the simplest and most secure choice. Memory tip: “JWT for OIDC, no Lambda needed” — if the token is a standard JWT from an external issuer, let API Gateway handle the validation.
SAA-C03 Design Secure Architectures Practice Question
This SAA-C03 practice question tests your understanding of design secure architectures. 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.
A public API for a B2B file exchange site is deployed on API Gateway. Clients must authenticate with standards-based tokens issued by an external OpenID Connect provider. Which authorization mechanism should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
JWT authorizer configured for the OpenID Connect issuer
Option C is correct because API Gateway's JWT authorizer natively validates JSON Web Tokens issued by an external OpenID Connect (OIDC) provider. It verifies the token's signature, expiry, and issuer against the OIDC provider's JWKS endpoint without requiring custom Lambda code, making it the simplest and most secure choice for standards-based token authentication.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
API keys only
Why it's wrong here
API keys identify clients for usage plans but do not authenticate users securely.
✗
IAM authorization for all internet users
Why it's wrong here
IAM authorization is suited to AWS principals, not general OIDC-authenticated application users.
✓
JWT authorizer configured for the OpenID Connect issuer
Why this is correct
A JWT authorizer validates tokens from a trusted OIDC issuer with low operational overhead.
Related concept
Read the scenario before looking for a memorised answer.
✗
A VPC endpoint policy
Why it's wrong here
Endpoint policies restrict private endpoint use, not public API user authentication.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse API keys (which are for rate limiting and client identification) with authentication, or assume IAM authorization can be used for external users, but IAM requires AWS credentials and is not designed for third-party OIDC tokens.
Detailed technical explanation
How to think about this question
The JWT authorizer in API Gateway uses the OpenID Connect Discovery URL to fetch the issuer's JWKS (JSON Web Key Set) and automatically caches the public keys for token signature verification. It supports RS256, RS384, RS512, and ES256 algorithms, and can validate custom claims like 'aud' (audience) to restrict token usage. In a B2B scenario, this allows each partner to use their own OIDC provider (e.g., Azure AD, Okta) while API Gateway handles token validation without custom code.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design Secure Architectures — This question tests Design Secure Architectures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: JWT authorizer configured for the OpenID Connect issuer — Option C is correct because API Gateway's JWT authorizer natively validates JSON Web Tokens issued by an external OpenID Connect (OIDC) provider. It verifies the token's signature, expiry, and issuer against the OIDC provider's JWKS endpoint without requiring custom Lambda code, making it the simplest and most secure choice for standards-based token authentication.
What should I do if I get this SAA-C03 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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. A public API for a financial reporting platform is deployed on API Gateway. Clients must authenticate with standards-based tokens issued by an external OpenID Connect provider. Which authorization mechanism should be used?
medium
✓ A.JWT authorizer configured for the OpenID Connect issuer
B.IAM authorization for all internet users
C.API keys only
D.A VPC endpoint policy
Why A: Option A is correct because the scenario requires standards-based token authentication from an external OpenID Connect (OIDC) provider. API Gateway's JWT authorizer can validate JSON Web Tokens (JWTs) directly against the OIDC issuer's well-known configuration (JWKS URI) without custom Lambda code, making it the simplest and most secure choice for token-based authentication.
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This SAA-C03 practice question is part of Courseiva's free Amazon Web Services 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 SAA-C03 exam.
Question Discussion
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