Question : Certificates from Enterprise Root CA from parent domain to clients in child domain.

Can we issue certificates from Enterprise Root CA which is in parent domain to clients in child domain?

Currently, we have Enterprise Root CA installed in child domain xyz.abc.com. We want to remove this CA and set up a CA in the parent domain abc.com to issue certificates for both parent and child domain.

What is the best practice?

Answer : Certificates from Enterprise Root CA from parent domain to clients in child domain.

It is possible yes (http://support.microsoft.com/kb/281271), but from a security and flexibility standpoint I would probably install an offline Root CA in the forest root domain, and a subordinate issuing CA in the child domain.

http://technet.microsoft.com/en-us/library/cc737834%28WS.10%29.aspx