title: PHP - Will the $_SERVER['SERVER_ADDR'] variable always be unique and never change?
body: <p>I have three quick questions regarding the PHP <code>$_SERVER['SERVER_ADDR']</code> variable. Will the variable be unique(only one on the whole internet)? Will the variable never change? If either of these questions is no, is there a way to identify the server uniquely on the internet via PHP?</p>