ChrE ChrE - 1 month ago 10
HTTP Question

Can HTTP-header LAST-UPDATED be trusted?

I have been using Rex Swain's HTTP Viewer to verify that none of the texts on a certain webpage has been changed recently.

The response was: "Code last updated 21 January 2012", so as I understand it, I can't really assume that anything was actually changed on that date but is it safe to assume that none of the texts on the webpage has been changed since that date?

I am not an HTTP expert, so please use layman terms where possible, thanks :-)

BR

Answer

A web server typically uses the corresponding file's last updated attribute as the value for the HTTP Last-Modified header, so in general it can be trusted, but it's always possible that the date is wrong, for whatever reason.

The Last-Modified header is usually used for caches, to populate the If-Modified-Since header in subsequent requests.