Tenants in the US Government, China and Germany clouds do not currently support the Office 365 CDN. The Office 365 CDN is only available to tenants in the Production (worldwide) cloud. The Office 365 CDN uses the HTTP/2 protocol for improved compression and download speeds. The built-in Office 365 Content Delivery Network (CDN) allows Office 365 administrators to provide better performance for their organization's SharePoint Online pages by caching static assets closer to the browsers requesting them, which helps to speed up downloads and reduce latency.