API Gateway

Question 1

Name four backend services that API Gateway can communicate with.

Answer 1

• Lambda
• Step Function
• EC2
• Elastic Beanstalk

Question 2

In API Gateway, what is API caching?

Answer 2

• It means that you Gateway caches your endpoint’s response.
• API Gateway then responds to a request by looking up the endpoint response from the cache instead of making a request to your endpoint.
• The response is cached for some TTL
• This can reduce the number of call made to your endpoint and improve the latency of the requests to your API

Question 3

What is Same Origin Policy?

Answer 3

• Under the policy, a web browser permits scripts contained in a first web page to access data in a second web page, but only if both web pages have the same origin.
• This is done to prevent Cross-Site Scripting attacks (XSS)
• Enforced by web browsers
• Ignored by tools like Postman and curl

Question 4

How can the Same Origin Policy be relaxed?

Answer 4

• By Cross-Origin Resource Sharing (CORS)
• With CORS, one server allows another server outside of the first servers domain to access restricted resources on the first server

Question 5

Does API Gateway scale?

Answer 5

Yes, API Gateway scales automatically.

Question 6

Name one way API Gateway uses to prevent attacks.

Answer 6

API Gateway can throttle to prevent attacks.

Question 7

How can you import APIs to API Gateway?

Answer 7

• Using the “API Gateway Import” feature.
• Allows you to import external definition files
• Currently, the Import API feature supports Swagger v2.0 definition files and Open API 3
• You can either create a new API by submitting a POST request that includes a Swagger definition in the payload and endpoint configuration
• or, you can update an existing API by using a PUT request that contains a Swagger definition in the payload
• You can update an API by overwriting it with a new definition, or merge a definition with an existing API
• You specify the options using a mode query parameter in the request URL

Question 8

What are the two default throttling limits used by API Gateway?

Answer 8

• 10.000 request per second or 5.000 concurrent requests
• These values are across ALL you APIs within an AWS account (or maybe it’s just for the 5.000?)
• You will receive a 429 Too Many Request error response if you go over any of these values

Question 9

Can API Gateway act as a SOAP web service passthrough?

Answer 9

Yes.

Question 10

Can you increase the throttling limit for API Gateway?

Answer 10

Yes, contact AWS Support.

Question 11

How/in what order are throttling rules applied?

Answer 11

• First, API Gateway checks against your account limit.
• If the traffic is below the set account limit, API Gateway checks the limit you have set on a stage or method.
• If the traffic is below the stage limit, then API Gateway applies the usage plans limits you set on per-API key basis.