The response headers returns with Google’s logo looks like this:
Content-Type: image/gif Last-Modified: Mon, 25 Apr 2005 21:06:18 GMT Expires: Sun, 17 Jan 2038 19:14:07 GMT Server: GWS/2.1 Content-Length: 8558 Date: Sat, 16 Jul 2005 01:52:05 GMT
And for some gif served by IIS on Win 2003 Server looks like this:
Server: Microsoft-IIS/5.0 X-Powered-By: ASP.NET Date: Sat, 16 Jul 2005 02:08:59 GMT Content-Type: image/gif Accept-Ranges: bytes Last-Modified: Fri, 04 Mar 2005 09:12:29 GMT Etag: "20bb944a9a20c51:acc" Content-Length: 3779
You can get this by using Web Developer Toolbar’s Information > Reponse Header button in Firefox.
Interesting things are:
- Google is not using Cache-Control: max-age=xxxx header which tells browser to cach the image for a while and not re-request from the server again. This is surprising because you would think Google would use every possible way out there to reduce the load on their server.
- Google has named their custom web server as Google Web Server, not surprisingly.