Caching
Proxy: Revalidation
GET /foo/index.html
HTTP/1.1
Host:
www.example.com
HTTP/1.1 304 Not Modified
GET /foo/index.html
HTTP/1.1
Host:
www.example.com
If-Modified-Since:
Thu, ...
Proxy
HTTP/1.1 200
OK
Last-Modified: Thu,
...
Content-Length:
3688
Content-Type:
text/html