setCookieDomain and setDomains

General questions
1

I’m new to custom dimensions

There is an example to add setCookieDomain and setDomains.
Is there any good example of statistics about how this will be seen?
Need help.

_paq.push([“setCookieDomain”, “*.mydomain.com”]);

_paq.push([‘enableLinkTracking’]);

_paq.push([“setDomains”, ["*.mydomain.com"]]);