Last-Modified response header not updated

Question

I have a problem with caching on my site. I make changes to the js file and publish it in my development environment (not verified at the moment). And I get an outdated version of my file.

If I use the page speed plugin for Firebug, I see that inside the response header for this particular JS file, the date of the last modification says yesterday about the date not today, as expected.

Also just out of curiosity, what is the Date field immediately after X-Powered-By?

Thanks!

Answer 1

The Date header is the date and time the response was sent (From Wikipedia ).

I don't like answering the question with the question, but is it possible that you have a caching firewall between you and the web server?