if-modified-since and last-modified

Tom Valley; (valley@ridgefield.sdr.slb.com)
Tue, 5 Aug 1997 07:35:57 -0400


Hi,

Apparently, some, if not most, web servers do not return the last-modified tag.
 However, I have noticed that all of them respond to the if-modified-since
method.  I can accurately measure if a page has been updated in the last 24
hours, even though the last-modified method fails every time.  Why is this?
 What value is this method examining, and is there a way to expose this value?
 Even for those sites that don't have the last_modified value defined, I'd like
to store the time of the last modification, if I can get it from this other
method.

Thanks...

Thomas