Various doubts & confusions related to MCSA

webspider

Hi all,
I have just started studying for MCSA but I have various doubts and confusions. Hope someone here will be kind enough to help me with these problems.
1)What is the difference between a DC,ADC(additional Dom. Contr.) and CDC(child domain controller) ? Do they have same powers (in terms of authentication etc.) is concerned? i.e. do they all provide the same authentication & directory services?
Is ADC & CDC located in the same domain tree as the DC but in different sites?
That is ,are they all (CD,ADC & CDC) located within the same domain tree?

2)What is the difference between a site and a domain tree? Are they the same thing?

3)I read this statement in book -
"A forest contains a single definition of network configuration and a single instance of the directory schema" -What does this mean?
How can one justify the above statement ? Because I think a "Forest" can contain multiple domain trees- if that is true -then how can a forest have a "SINGLE" definition of network configuration and a "SINGLE" instance of the directory schema ?? Since each domain tree can contain different schema and different network configuration,then a Forest should have multiple schemas and network configuration?

4)Does a child domain represent a different site compared to main domain? For example. - research.net & south.research.net.
Does the above represents two different domains? I know that the two comprise a tree and that south.research.net is a "Child Domain" to the parent domain "research.net"
Please correct me if I am wrong.

5)This is related to replication- If there is a DC,ADC and CDC connected by a router ,then how will changes be replicated ? Will it be between DC and ADC only?
Also,can replication occur between different domain trees like abc.com , test.com and xyz.net?

Thanks in advance
With Best Regards