Google Analytics Cross Domain Tracking and _setDomainName()

Question

I\'m trying to set up cross domain tracking between two totally different Domains (not sub-domains). Looking through different pages of Google\'s documentation seem to give

Answer 1

I thought mysite.com will track across that site and its 1st level subdomains (like mysite.com and cats.mysite.com), and .mysite.com will track across that site and its 1st AND 2nd level subdomains (like mysite.com and cats.mysite.com and store.cats.mysite.com).

I base that off what google and some other articles say.

none will disallow any subdomain tracking (so I assume it sets it to set the cookie's domain to: www.mysite.com).

Im guessing the default option auto will set it via document.domain to www.mysite.com (but maybe mysite.com if not on the www domain based on Eduardo's answer above/below to allow allow smarter 1st level subdomain tracking).

The auto/none are guesses from me, not sure what it would put for the domain if you came on blah.mysite.com and had those none/auto options set.