how does web server handle 304 http status code

Question

As i understand 304 status says the cache in browser is valid enough. So does the web server never send the page in case the page is not expired cache timing or does it process the request and send the page and also the status code?

Answer 1

According to http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html it states:

The 304 response MUST NOT contain a message-body, and thus is always terminated by the first empty line after the header fields.

What the RFC doesn't tell you is the conditions that trigger this response - and they will usually be based upon the browser sending a unique identifier (e-tag) that was sent by the web server previously and/or the browser sending a date along with the request of the cached version of the document.