I want to verify that the images, css, and javascript files that are part of my page are being cached by my browser. I’ve used Fiddler and Google Page Speed and it’s unclear whether either is giving me the information I need. Fiddler shows the HTTP 304 response for images, css, and javascript which should tell the browser to use the cached copy. Google Page Speed shows the 304 response but doesn’t show a Transfer Size of Zero, instead it shows the full file size of the resource. Note also, I have seen Google Page Speed report a 200 response but then put the word (cache) next to the 200 (so Status is 200 (cache)), which doesnt make a lot of sense.
Any other suggestions as to how I can verify whether the server is sending back images, css, javascript after they’ve been retrieved and cached by a previous page hit?
In browser HTTP debuggers are probably the easiest to use in your situation. Try HTTPFox for Firefox or Opera which has dragonfly built-in. Both of these indicate when the local browser cache has been used.
If you appear to be getting conflicting information, then wireshark/tcpdump will show you if the objects are being downloaded or not as it is monitoring the actual network packets being transmitted and received. If you haven’t looked at network traces before, this might be a little confusing at first.