CDN Origin Host Header misguided instructions and required field
If you front a blob store with a Azure CDN then by default it does not work, you are required to enter a Origin host header before it works. This then should be a required field. Also the tool tip hint in the portal for the origin is very confusing "Azure CDN origins, such as Web Apps, Blob Storage, and Cloud Services, require this host header value to match the origin hostname by default." Using 'required' and 'default' is bad wording in this situation. There are many people falling into this trap from a quick search on the internet.