define('DOMAIN_CURRENT_SITE', 'domain.com' );

I have a doubt; but the “DOMAIN_CURRENT_SITE” variable and table value “domain=domain.com” can be set with different values?
This beacause domain can be set as “domain.com”, but the “DOMAIN_CURRENT_SITE” variable, can’t.
If I try to set “DOMAIN_CURRENT_SITE” as “domain.com” the main blogs url in dashboard are brokens (point to domain.com).
This is true with WP 3.1 while with version 3.0.1 works fine.
Also, if i set:
define(‘DOMAIN_CURRENT_SITE’, ‘blog.domain.com’ );
I can create only blog like “newblog.blog.domain.com”

with
define(‘DOMAIN_CURRENT_SITE’, ‘domain.com’ );
I can create only blog like “newblog.domain.com” (that’s what I want)

So the question is: can I set the DOMAIN_CURRENT_SITE with main domain name like “domain.com”?

Thanks.