Its is recommended just because in case of one fails other server can take over the roles and the network does not crash down.
2
replication
DomainDNSzones
You run the 'dcpromo' command to remove active directory and demote a domain controller to a member server. To remove AD completely you would have to do this process on all domain controllers.
Policy Change Events.
Active Directory is called active bacause it is actively updating it's data through replication from differnt sites and other domain controllers with in the network
Yes all domain controllers 2003, 2008 are writable except when its 2008 RODC..
Policy Change Events.
Active Directory in general uses a multimaster scheme for updating the directory databases between domain controllers, there are specific functions that can only be performed on specific domain controllers. These specific functions are assigned to one of the five FSMO roles, (pronounced "fiz-moe roles") which can be assigned to one or more Domain Controllers.
Read Only
Outbound replication is when a domain controller transmits replication information to other domain controllers on a network andInbound replication is when a domain controller receives updates to the Active Directory database from other domain controllers on the network.
Service Intergration protocol (SIP)
Functional levels