- A
Modify the Lambda authorizer to fetch the public key from a well-known URL at runtime.
This allows the authorizer to always use the latest key without manual updates.
- B
Update the API Gateway stage deployment to redeploy the API.
Why wrong: Redeploying does not update the authorizer's key; it only deploys the current configuration.
- C
Delete and recreate the API Gateway authorizer with the new key.
Why wrong: This causes downtime and is not efficient.
- D
Update the Lambda authorizer's environment variable with the new key and publish a new version.
Why wrong: This works but is less efficient than dynamic key retrieval because it requires manual updates each time the key changes.
Question 1,487 of 1,616
Lambda Authorizer JWT Key Rotation
This DVA-C02 practice question tests your understanding of development with aws services. 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 company uses Amazon API Gateway to expose a REST API. The API uses a Lambda authorizer to validate JWT tokens. Recently, the API has been returning 401 Unauthorized errors for valid tokens. The developer notices that the tokens are signed with a new key but the authorizer still uses the old key. What is the MOST efficient way to update the authorizer with the new key?
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
✓
Modify the Lambda authorizer to fetch the public key from a well-known URL at runtime.
Option A is correct because fetching the public key from a well-known URL (e.g., the JWKS endpoint) at runtime allows the Lambda authorizer to automatically use the latest signing key without manual intervention. This approach decouples key rotation from the authorizer code, ensuring that valid tokens signed with the new key are accepted immediately. It is the most efficient method as it avoids redeployments, environment variable updates, or recreating the authorizer.
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.
- ✓
Modify the Lambda authorizer to fetch the public key from a well-known URL at runtime.
Why this is correct
This allows the authorizer to always use the latest key without manual updates.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Update the API Gateway stage deployment to redeploy the API.
Why it's wrong here
Redeploying does not update the authorizer's key; it only deploys the current configuration.
- ✗
Delete and recreate the API Gateway authorizer with the new key.
Why it's wrong here
This causes downtime and is not efficient.
- ✗
Update the Lambda authorizer's environment variable with the new key and publish a new version.
Why it's wrong here
This works but is less efficient than dynamic key retrieval because it requires manual updates each time the key changes.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume updating environment variables or redeploying the API is sufficient, but they overlook that the authorizer must dynamically resolve the signing key to handle automatic key rotation without manual steps.
Detailed technical explanation
How to think about this question
Under the hood, a Lambda authorizer can be configured to fetch JSON Web Key Sets (JWKS) from a URL, such as `https://cognito-idp.{region}.amazonaws.com/{userPoolId}/.well-known/jwks.json`. The authorizer caches the JWKS for a configurable TTL (default 300 seconds) to reduce latency, but will fetch new keys after the cache expires. This pattern is essential for environments where identity providers rotate signing keys regularly, as it eliminates the need to redeploy or reconfigure the authorizer for each rotation.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the Lambda authorizer to fetch the public key from a well-known URL at runtime. — Option A is correct because fetching the public key from a well-known URL (e.g., the JWKS endpoint) at runtime allows the Lambda authorizer to automatically use the latest signing key without manual intervention. This approach decouples key rotation from the authorizer code, ensuring that valid tokens signed with the new key are accepted immediately. It is the most efficient method as it avoids redeployments, environment variable updates, or recreating the authorizer.
What should I do if I get this DVA-C02 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.
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Last reviewed: Jul 4, 2026
This DVA-C02 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 DVA-C02 exam.
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