Entity Tags(Etags) in asp.net - ETag vs Header Expires Introduction Entity Tags (ETags) are commonly used in Web applications to effectively leverage the power of using web farms, which is a non-fancy term for HTTP/S load balancing. In web farms, a common practice is to set what is called ETags as it helps enhance performance in web farm scenarios. ETags is controlled in IIS by a metabase property (ETAG_CHANGENUMBER) and this value is sent back to clients via response headers as instructed by the HTTP RFC 2616 . If the ETag value is the same across a number of servers, then clients are not required to re-download content that already exists in the clients cache. Without this value set to the same, clients might communicate on subsequent requests to another server in the web farm and receive an unnecessary response of data from the IIS server. For purposes of this blog, I will focus o...
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