This chapter reviews the physical structures of Active Directory. This chapter also introduces you to the relationships between domain controllers, the various roles of domain controllers, global catalogs, and sites. | Active Directory Physical Structure his chapter reviews the physical structures of Active Directory. This chapter also introduces you to the In This Chapter The Concept of Sites Active Directory Replication Active Directory Topology relationships between domain controllers the various roles of domain controllers global catalogs and sites. Past Present and Future Past operating systems had no awareness of the underlying physical network structure on which they were deployed. For small companies even reasonably sized ones the network layout interconnection points and subnets remote offices and so on were either laid out long before Windows NT became pervasive or were installed independently of the network operating systems that depended on it. We typically build networks on which the servers reside on 100Mbps media the backbone. There is 100Mbps media between floors and then this network is extended into a 10Mbps network down to the users. Windows NT does not care if the network is 10Mbps or 10 000Mbps . . . it has no built-in means of catering to the available resources. But this is no longer sufficient because Windows 2000 s physical structure and its multi-master replication technology global catalog services public key infrastructure directory synchronization Kerberos authentication and more do need to be sensibly and carefully built according to the physical network resources. Fortunately the OS also allows you to build a logical network and map it to a present or future physical network. With Active Directory services you can tailor your Windows 2000 deployment to the available network and merge the two structures into a unified cooperative. The reason for this is Active Directory and its host domain controller server. 266 Part III Active Directory Services Windows NT and Windows 2000 network requirements are very different. Windows NT depends on a single primary domain controller the PDC which holds the master database of the domain configuration accounts .
