Check if file has been changed on dynamic website

I am writing a function, which downloads a zip file from a website every single day, only if the file has been updated. Is there any way for me to find if the file has been changed without downloading it? There is also a table generated on the same website, so I was thinking, check if there are new values in the table, if true, then download the file.
Is there any other approach I could find useful? Unfortunately, I cannot publish the website I am downloading the file form.