Active Directory Connections

I just finished adding my 1st Ex2000 server into my 5.5 site.. looks great, but, I have two sites in my 5.5 org. I setup an initial CA between my
exchange server and the AD.. worked great. Now,
I use to have the users from the 2nd site appear in the AD. I can no longer find them in the global address book or send email without fully qualify DNS name. Do I need a CA for them to the AD also.. It would pull them over an disabled acounts but would show email address and them in the GAL…