- A
Enable caching for the Lambda authorizer responses.
Caching avoids invoking the authorizer for every request.
- B
Use a custom authorizer instead of a Lambda authorizer.
Why wrong: Custom authorizers are not available in API Gateway.
- C
Reduce the TTL of the authorizer cache.
Why wrong: Reducing TTL would increase authorizer invocations.
- D
Increase the memory allocated to the Lambda authorizer function.
Why wrong: Increasing memory may help but caching is more effective.
Question 261 of 1,616
Reducing Lambda Authorizer Latency by Enabling Response Caching
This DVA-C02 practice question tests your understanding of development with aws services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 with a Lambda authorizer to control access to its APIs. The Lambda authorizer returns an IAM policy that grants access to the API. Recently, the company noticed that some API calls are being throttled due to high latency from the authorizer. What is the MOST effective way to reduce latency?
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
✓
Enable caching for the Lambda authorizer responses.
Enabling caching for the Lambda authorizer responses allows API Gateway to reuse the IAM policy returned by the authorizer for subsequent requests that match the same cache key, without invoking the Lambda function again. This eliminates the latency of the authorizer invocation on cache hits, directly addressing the throttling caused by high authorizer latency.
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.
- ✓
Enable caching for the Lambda authorizer responses.
Why this is correct
Caching avoids invoking the authorizer for every request.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a custom authorizer instead of a Lambda authorizer.
Why it's wrong here
Custom authorizers are not available in API Gateway.
- ✗
Reduce the TTL of the authorizer cache.
Why it's wrong here
Reducing TTL would increase authorizer invocations.
- ✗
Increase the memory allocated to the Lambda authorizer function.
Why it's wrong here
Increasing memory may help but caching is more effective.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume increasing Lambda memory (Option D) is the universal fix for Lambda performance issues, but in this context the latency stems from the invocation overhead and network round-trip, not from CPU-bound processing, making caching the more effective solution.
Detailed technical explanation
How to think about this question
API Gateway Lambda authorizer caching works by generating a cache key from the request parameters (e.g., method ARN, identity source) and storing the returned IAM policy for the configured TTL (default 300 seconds). On a cache hit, API Gateway applies the cached policy directly, bypassing the Lambda invocation entirely. This is especially effective in scenarios where the same user or token makes repeated calls within the TTL window, such as during paginated API calls or token refresh intervals.
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.
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: Enable caching for the Lambda authorizer responses. — Enabling caching for the Lambda authorizer responses allows API Gateway to reuse the IAM policy returned by the authorizer for subsequent requests that match the same cache key, without invoking the Lambda function again. This eliminates the latency of the authorizer invocation on cache hits, directly addressing the throttling caused by high authorizer latency.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on DVA-C02
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 company uses Amazon API Gateway with a Lambda authorizer to secure its APIs. The authorizer must verify a JWT token from a third-party identity provider. The team notices that the authorizer is called on every API request, causing additional latency. How can the team reduce the number of authorizer invocations?
medium- A.Use Amazon CloudFront to cache the API responses.
- ✓ B.Configure the Lambda authorizer to return a cached policy using the 'methodArn' and 'principalId' combination.
- C.Enable API Gateway caching and set a TTL of 300 seconds.
- D.Remove the Lambda authorizer and use IAM roles for authorization.
Why B: Option B is correct because Lambda authorizers can return a cached IAM policy using the 'methodArn' and 'principalId' combination, which tells API Gateway to reuse the policy for subsequent requests to the same resource and principal without re-invoking the authorizer. This reduces latency by avoiding redundant JWT verification calls to the third-party identity provider on every API request.
Keep practising
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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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