An origin server is the physical location from which content is retrieved. It is required in all configurations that retrieve content from an origin.
About the Origin Server and AMD
This is a mandatory behavior. You can't delete it from the Default Rule. (An error message is revealed if you delete it, and you need to re-add it.) However, you can also include the Origin Server behavior in lower-level, or nested "Custom Rule." This lets you override the Default Rule in favor of an alternate origin for various purposes: authorization requests, redirects for downloads, access-denials, failover settings, redirects for special user agents, language settings or for other needs.
The origin server is not necessarily your asset. It can also be a directory within a NetStorage storage group. So, available settings in this behavior vary based on the selected Origin Type.
How do I configure this behavior?
Select the appropriate Origin Type from the drop-down and configure additional options. Complete details are discussed in the Property Manager documentation.