Why some sites redirect to an url with a random parameter when you connect?

When I visit a site with critical services (for example an online shopping website) and go to login page (http://ift.tt/2gTRipe) sometimes it redirects to another url with a random parameter in query string (https://site_example_login/disp?random=31234 for example).

Is it a prevention from some type of attack (such as CSRF?) or something about used web technologies of that site?

Thanks in advance