It’s an attempt to disable caching. The date is the birthday of the developer Sascha Schumann who added the code. From session.c: Authors: Sascha Schumann <sascha@schumann.cx> Andrei Zmievski <andrei@php.net> // … CACHE_LIMITER_FUNC(private) { ADD_HEADER(“Expires: Thu, 19 Nov 1981 08:52:00 GMT”); CACHE_LIMITER(private_no_expire)(TSRMLS_C); }
The easiest way to add these headers is a .htaccess file that adds some configuration to your server. If the assets are hosted on a server that you don’t control, there’s nothing you can do about it. Note that some hosting providers will not let you use .htaccess files, so check their terms if it … Read more
They are slightly different – the ETag does not have any information that the client can use to determine whether or not to make a request for that file again in the future. If ETag is all it has, it will always have to make a request. However, when the server reads the ETag from … Read more