Which of the following backend service types does API Gateway support?

API Gateway supports the HTTP(s) service backend type, enabling it to facilitate communication between clients and various services. This service type is critical because API Gateway acts as an intermediary for HTTP requests, managing incoming API calls, validating them, and routing them to the appropriate backend service seamlessly.

By supporting HTTP(s) services, API Gateway can connect and interface with a wide range of applications and microservices that communicate over HTTP, which is the fundamental protocol for data exchange on the web. This capability is essential for building modern APIs that need to interact with RESTful architectures, ensuring compatibility with numerous web-based services.

The other backend service types listed do not align with the primary function of an API Gateway. For example, while SMTP is utilized for sending emails, it does not pertain to the execution of web APIs. Static file services are typically served through content delivery networks (CDNs) or web hosts and are not specifically designed for API interaction. Data warehouses focus on long-term storage and analytics of large datasets and are not typically accessed via an API Gateway in the same manner as HTTP services. Hence, the clear alignment of API Gateway functionality with HTTP(s) services underscores why this is the correct choice.