CA in a Multi-forest AD Environment

We are thinking about bringing up a CA within our organization for issuing certs to computers,  and I have a question about Microsoft CA Service.  We have a total of 7 AD forests in our organization and there are no trusts established among them.  After reading through Microsoft whitepaper, it seems to me the best approch (for us) is setting up one offline standalone CA and one to two enterprise subordinate CA's for each forest in our environment. Can this work?  Would I be able to publish the root CA's CDP and AIA and set up subordination to multiple AD forests?   I was not able to find anything regarding how CA should be set up in a multi-forest AD environment.  Please help.
shong1997Asked:
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CoccoBillCommented:
Enterprise CAs are tied to a forest, but standalone CAs can span multiple forests. Create a standalone offline root CA and one or more enterprise subordinate issuing CAs per forest. The offline root should be standalone anyway, since a domain member will be removed from the domain after 90 days offline, which would essentially irreparably kill it.

From the client's point of view the Sub/Issuing CA is the only one they care about, they never need to access the root. CDPs and AIAs can be set on a per server basis, so it shouldn't be a problem to point the certs issued on each CA to look for them in the local forest. The offline root only issues the CA certs to the sub-CA's, and CDP/AIA will point to the offline server. This isn't a problem, and you'll be updating the CRLs and renewing CA certs manually anyway. Trust relationships are not required, but as you probably know, cersvc uses RPC so 135/tcp and high ports over 1024 need to be open.

Here's a couple good links for additional information:
http://technet.microsoft.com/en-us/library/cc737834.aspx
http://technet.microsoft.com/en-us/library/cc728390.aspx
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