When API Gateway executes a request against a remote server, it issues an HTTP or HTTPS request to the specified target server. If your API Gateway instance is behind a firewall, and must route these HTTP or HTTPS requests through a third party proxy server, you can configure proxy servers to which API Gateway routes these requests.

For API Gateway to use a proxy server, you must define a proxy server alias. The proxy server alias identifies a proxy server and a port on the server through which you want to route requests. You can configure API Gateway to route requests to one or more proxy server aliases for each type of outbound requests (HTTP, HTTPS).

All the configured and available proxy server aliases are listed in a table with the corresponding details of the port being used, the host on which it is, the protocol used, and so on. To use a proxy server you have to enable it.