API Gateway quiz · Level 0 · Todo.io Learns AWS

Question 1Todo.io's backend runs on Lambda. Browsers need an HTTPS address to send requests to. What should sit in front of the function?

Amazon API Gateway.Correct. API Gateway gives you a managed HTTPS endpoint and passes each request to Lambda: the classic serverless API.A public IP address on the function.Not this one. Lambda functions don't have IP addresses you can call.Put the function in a public subnet.Not this one. A subnet doesn't give a function an HTTPS endpoint.An SQS queue.Not this one. A queue holds work for later. A browser waiting for an answer needs a request and a response.

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Question 2A buggy client starts sending thousands of requests a second to Todo.io's API. Which API Gateway feature protects the backend?

Throttling: a rate limit that rejects excess requests before they reach the backend.Correct. Extra requests get HTTP 429 (Too Many Requests) and never reach Lambda or the database.Logging every request to CloudTrail.Not this one. CloudTrail records AWS API calls; it doesn't stop anything.A WebSocket API.Not this one. That keeps connections open; it doesn't limit how many requests arrive.A longer Lambda timeout.Not this one. That makes each request last longer, which is worse under a flood.

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Question 3Todo.io's API Gateway invokes its Lambda function. In Todo.io's setup, which policy says that API Gateway may invoke the function?

A resource-based policy on the function.Correct. It lives on the function and names the caller (apigateway.amazonaws.com): who may use this resource.The function's execution role.Not this one. The execution role says what the function may do, not who may call it.An SCP on the account.Not this one. SCPs only cap permissions; they never grant them.A security group on the function.Not this one. Security groups filter network traffic. Invoking a function is an AWS API call, decided by IAM.

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Question 4Todo.io wants an API with no servers to patch or scale. Which combination is the classic serverless pattern?

API Gateway → Lambda → DynamoDB.Correct. Every piece is managed and scales on its own; you pay for requests, not idle servers.EC2 → RDS.Not this one. Both run on servers you size, and EC2 you also patch.API Gateway → EC2 → RDS.Not this one. EC2 still means servers to manage.SQS → CloudWatch Logs.Not this one. That is a queue and a log store; neither serves an API.

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Question 5Which of these does API Gateway handle for Todo.io?

The HTTPS endpoint, throttling and authorisation, before requests reach the backend.Correct. It is the front door; your code behind it does the actual work.Storing the todos.Not this one. Data lives in a database such as DynamoDB or RDS.Running the business logic.Not this one. That runs in the backend, usually Lambda.Patching the backend's servers.Not this one. With Lambda there are none; with EC2 that is still your job.

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Question 6Where does Todo.io's public API Gateway endpoint run, relative to its VPC?

Outside the VPC, as a managed AWS service with its own public endpoint.Correct. Like DynamoDB and SQS, it is a public AWS service. It doesn't need your subnets or a NAT gateway.Inside one of the VPC's public subnets.Not this one. API Gateway doesn't run in your subnets.Inside a private subnet, reached through a NAT gateway.Not this one. NAT is for things inside the VPC calling out, not for a public front door.On an EC2 instance that Todo.io launches.Not this one. It is fully managed; there is no instance to launch.

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Question 7What does "API Gateway" mean?

A managed HTTPS front door that passes requests to your code.Correct. Think of it as: A receptionist who takes every visitor's request and phones the right person.Upload a function; AWS runs it only when something calls it.Not this one. That describes Lambda.An API Gateway API that keeps each browser connection open, so your backend can push messages at any time.Not this one. That describes WebSocket (API Gateway WebSocket API).Run containers on AWS. With Fargate, AWS also runs the servers underneath.Not this one. That describes ECS and Fargate.

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Question 8Which term is this? "A managed HTTPS front door that passes requests to your code."

API GatewayCorrect. Yes. Think of it as: A receptionist who takes every visitor's request and phones the right person.LambdaNot this one. Lambda is: Upload a function; AWS runs it only when something calls it.WebSocket (API Gateway WebSocket API)Not this one. WebSocket (API Gateway WebSocket API) is: An API Gateway API that keeps each browser connection open, so your backend can push messages at any time.ECS and FargateNot this one. ECS and Fargate is: Run containers on AWS. With Fargate, AWS also runs the servers underneath.

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Question 9Which AWS term is described by this analogy? "A receptionist who takes every visitor's request and phones the right person."

API GatewayCorrect. Yes: A managed HTTPS front door that passes requests to your code.LambdaNot this one. Lambda is: Upload a function; AWS runs it only when something calls it. Its analogy: A taxi. You pay for the ride, not for owning the car.WebSocket (API Gateway WebSocket API)Not this one. WebSocket (API Gateway WebSocket API) is: An API Gateway API that keeps each browser connection open, so your backend can push messages at any time. Its analogy: An open phone line instead of sending letters back and forth.ECS and FargateNot this one. ECS and Fargate is: Run containers on AWS. With Fargate, AWS also runs the servers underneath. Its analogy: Handing over a packed lunchbox and letting someone else heat it up.

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