configuring e-tags

Question

I am using Yslow as a simple speed benchmarking tool and I came across a really confusing concept. The E-tag

So the main problem is : How do I configure E-tags? my grade

Answer 1

Entity tags are a feature of the HTTP protocol, see http://www.ietf.org/rfc/rfc2616.txt

Entity tags are used for comparing two or more entities from the same requested resource. HTTP/1.1 uses entity tags in the ETag (section 14.19), If-Match (section 14.24), If-None-Match (section 14.26), and If-Range (section 14.27) header fields. The definition of how they are used and compared as cache validators is in section 13.3.3. An entity tag consists of an opaque quoted string, possibly prefixed by a weakness indicator.