The last paragraph of the post explains why Last-Modified should be provided if possible.

The images on your site have an appropriate Expires header, but you haven’t set Expires for many of the CSS and Javascript files.

Site: growth trac dot com

Site-wide, we’re using this:

Our pages are *.php — mostly static with some dynamic elements.

QUESTIONS
– Do we need to use a Last-Modified header?
– Do the above settings look “okay” ?

Also –

I’ve read different opinions on the use of
“max-age” vs “expires”

Some say: use both or use the “max-age” (more reliable?)

– What do you say?
Thanks for an excellent article.

Yes, the HTTP response headers are separate from the HTML. You would need to set them for static files in IIS or whatever web server you are using.

With dynamically generated content (e.g. ASPX) you can specify the headers programmatically.

if i use just a plain .html file, what then?
Where do i write ‘no-cache’ code?
in a separate default.aspx file?

I cannot do it in html: “Cache-Control: no-cache” is not html language. And all i know is html.

what am i missing?