ACTIVE DIRECTORY SITES

             A site refers to a physical location of a domain network. The concept of sites is introduced to help in configuring replication taking place between DCs located far-away and connected through a slow WAN link.
            A single site can have many domains. A single domain can also span many sites.



         Replication takes place between two or more domain controllers (DCs).Replication between DCs can be of two types:

1. Intrasite Replication: - It is a replication between DCs present within a site or within the same domain network.
2. Intersite Replication: - It is a replication between remote DCs or DCs located in different sites.

DIFFERENCES BETWEEN INTRASITE & INTERSITE REPLICATION
 Intra-site Replication
1. It happens within a site.
2. It is very fast as the DCs are connected to the LAN link.
3. The protocol RPC (Remote Procedure Call) is used for Replication.
4. Data Compression is not used.
Inter-site Replication
1. It happens between remote sites.
2. It is very slow as the DCs are connected to the WAN link.
3. The protocol IP or SMTP is used for Replication. IP stands for Internet Protocol and SMTP stands for Simple Mail Transfer Protocol.
4. Data is sent in a compressed form so that it can be moved quickly across slow WAN link.
                         There is no need to configure Intra-site replication as it is very fast and it takes place automatically. But Inter-site replication is needed to be configured as it is slow because data has to travel through the WAN link. The Inter-site replication is scheduled and concept of sites helps in configuring Inter-site replication.

                          DCs participating in the Inter-site replication are called Bridgehead servers. In the diagram, DC3 and DC4 are bridgehead servers.
                   To configure Inter-site replication between these two remote DCs, i.e., DC3 and DC4, go to programs > administrative tools > Active Directory Sites and Services.