Child Domain Controller & Additional Domain

what differences between child domain controller & additional domain controller ? 

i figure best use microsoft's explanations this.

child domain

domains subsequently created in given windows 2000 , windows server 2003 domain hierarchy become child domains of root domain. example, if msdn child domain of microsoft.com, msdn domain becomes msdn.microsoft.com.

http://support.microsoft.com/kb/310996

additional domain controllers

if have 1 domain controller in domain, can add additional domain controllers domain improve availability , reliability of network services. adding additional domain controllers can provide fault tolerance, balance load of existing domain controllers, , provide additional infrastructure support sites.

http://technet.microsoft.com/en-us/library/cc738032(ws.10).aspx

Windows Server  >  Windows Server General Forum