Does Apache use file timestamps to check whether a resource has been modified?

Question

I am developing an html page referencing a large Javascript file (1MB+) which is seldom modified. From here, I get that the js file will not be resent if not modified.

My question is: how does Apache checks whether an ftp uploaded javascript file has been modified? Is it from its file timestamp? If not, where does it get this information? I want to understand the process to control performance issues.

Answer 1

For static files, a call to stat() is typically used to check if the file size or modification time has changed.

The Caching Guide goes into detail and also contains the above reference in the section A Brief Guide to Conditional Requests.