The Origin Protocol option of CDN Static services allows you to set protocol for pull requests from CDN edge servers to your origin server.
How to set Origin Protocol
Origin Protocol can be set during a CDN service creation (in advanced settings) or on the Services/Settings page.
Select HTTP, HTTPS or Automatic (80/443) from the Origin Protocol select box as in the picture below.
How automatic protocol works
When Origin Protocol is set to Automatic (80/443) then the protocol used by CDN edge servers to pull content from your origin server is determined by the protocol used in the corresponding CDN URL.
Let's assume that you have created a CDN Static service with Service Domain cdn.mycompany.com and that Origin Protocol is set to Automatic (80/443).
- When a viewer requests http://cdn.mycompany.com/favicon.ico then the corresponding edge server will pull the content from your origin server over HTTP protocol (port 80).
- When a viewer requests https://cdn.mycompany.com/favicon.ico then the corresponding edge server will pull the content from your origin server over HTTPS protocol (port 443).
Please note that Origin Protocol set to Automatic (80/443) is helpful only if the CDN service has SSL enabled. Please refer below for more details.
Secondary Origin Domains
When Secondary Origin Domains (IP addresses) are set then the same protocol is used for pull requests to all your origin IP addresses.
Please note that HTTPS origin protocol does not imply that the CDN service has (shared or custom) SSL enabled. You can always access your CDN content over both HTTP and HTTPS protocols but if SSL is not enabled for the CDN service then access over HTTPS protocol will throw an SSL error. It follows that Origin Protocol set to Automatic (80/443) is helpful only if the CDN service has SSL enabled.
Please refer to Creating CDN services with an SSL enabled for more details on how to enable SSL for a CDN Static or CDN Static Push service.
Please note that a self-signed SSL certificate is allowed to be used on origin.
Custom origin port
Please note that when Origin Protocol is set to Automatic (80/443) then you can not set custom origin port, ports 80 and 443 will be used.
Read about Setting an Origin Port.