Understanding trees, forests, etc in AD


I am having a little trouble getting my head around forests, trees etc in AD.

So, I will give an example structure below and hope someone can help.

Let say my organisation is named Company.

I have one AD forest. If I look at the domain structure using ADUC, then I see two 'root' domains; Europe.company.com and US.Company.com

Europe.Company.com has child domains of UK.europe.company.com, France.europe.company.com and Germany.europe.company.com

In addition, UK.europe.company.com itself has two child domains of London.UK.Europe.company.com and Manchester.UK.Europe.Company.com

US.Company.com has two child domains; East.US.Company.com and West.US.Company.com

Would I be correct in saying there were two Trees here? Europe.Company.com and US.Company.com.

But what are the Leaves? And are there any other terms?

Also, what is the Forest root?

Any help appreciated!
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Company.com would be considered your forest, and europe.company.com and us.company.com are the trees.  There are no branches or leaves.  The link below provides a good explanation of them:


If you google act. dir. forests and trees, you can find a lot of reading material on the subject.

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bruce_77Author Commented:
Thanks...so what is the Forest Root - europe.company.com or us.company.com - or would it depend on which was created first?
You have one forest company.com. The rest are just child domains. The forest root is the fist domain you have created like company.com, assuming this is the domain name. A forest with multiple tress usually consist of different domain names in the same forest such as compan1.com, company2.com etc.
See reference: http://technet.microsoft.com/en-us/library/dd441359(office.13).aspx
Here are more references:
Acttive Dorectory Logical Models:

Expand the title of this link you will see other topics:
Single Forest and Single-domain model
Single Forest and Multiple-domain model
Multiple-Forests - Super Admin domain model
Multiple-FOrests - Super Admin Forest Model
bruce_77Author Commented:
Thanks guys.

Apparently, I've been told that we actually have two forests - Europe.company.com and US.company.com are two seperate forests, with a 2 way trust between them.

Is there any tool/view I can use to find out if we actually do have two forests or not?
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