ETag or entity tag is a part of HTTP. It is one of the mechanisms that HTTP provides for web cache validation, and which allows a client to make conditional requests. This allows caches to be more efficient and saves bandwidth because a web server does not need to send a full response if the content has not changed.
Our nodes support ETag header by default. Please note that the automatic content validation by ETag is not provided. If you want to renew content on CDN servers, purge the cache.
By default, all HTTP headers on the origin will be inherited by a CDN. You can manage HTTP headers in the control panel if you like.