How to set cookie ONLY for my domain, except subdomains

[eluser]Mareshal[/eluser]
When using ySLow I found this: http://developer.yahoo.com/performance/r...ookie_free

They recommend us to use another domain, or a subdomain to server static content. I was wondering if this code affect static.my-domain.com? I want to set cookie for main domain, but impossible to read from subdomains.

Code:

$config['cookie_prefix']    = "";
$config['cookie_domain']    = ".my-domain.com";
$config['cookie_path']        = "/";