In the same way that your web browser has a cache of recent web pages, your Internet Service Provider (ISP) may be doing some caching on your behalf.
In some (rare) cases, even though you are using shift-refresh to get new data from a webpage, the pages still seem to be old.
On this site you can find step by step guides for Chrome, Firefox 3, Firefox 2, Internet Explorer 8, Internet Explorer 7, Internet Explorer 6, Safari and more on how to refresh your cache.
Someone just told you to “force reload” your browser to fix something.
The server checks the token against the current resource.
If the token hasn't changed, the server returns a "304 Not Modified" response, which tells the browser that the response it has in cache hasn't changed and can be renewed for another 120 seconds.
Most times a simple force cache refresh won't work and you need to clear the cache by hand.
Assume that 120 seconds have passed since the initial fetch and the browser has initiated a new request for the same resource.
First, the browser checks the local cache and finds the previous response.
This may be because your Internet Service Provider also has a cache and their cache may not be set up quite right, and they are not downloading the latest web pages.
Fetching something over the network is both slow and expensive.