Bridgehead Server Role in Active Directory

Bridgehead Server : 

Hey guys lets discuss about Bridgehead Server in Active Directory, What is Bridgehead Server ? What exactly the bridgehead server responsible in Active Directory ?

So We all know that all domain controllers within the same site will participate in the replication process with each other, not all domain controllers will replicate with other sites simultaneously. This is because replicating Active Directory data between sites using all available domain controllers can be an extremely bandwidth-intensive operation. To further minimize the bandwidth implications of Inter-site replications, Active Directory will designate a bridgehead server within each site.

All traffic within a site is replicated to that site's bridgehead server. The bridgehead server is then responsible for replicating all changes that have taken place within that site to other bridgehead servers in remote sites. The Inter-site Topology Generator ( ISTG ) automatically assigns one server in each site as the bridgehead server unless you override this by establishing a list of preferred bridgehead servers. The advantage of administratively assigning a preferred bridgehead server list is that you can determine which servers have the best processing power and available network bandwidth for handling replication traffic. We should remember that intersite replication traffic is compressed by default, so the bridgehead servers will be responsible for decompressing, compressing, sending and receiving all replication traffic within the site and between sites. Configuring more than one preferred bridgehead server allows administrative control over the task of replicating between sites using the most efficient machines. When more than one preferred bridgehead server is configured and the preferred bridgehead server fails, the KCC will choose another server from the list.

When planning the use of bridgehead servers, we must consider the following guidelines: 

--> Configure a list of preferred bridgehead servers to assist in better performance from site to site. Servers should be chosen based on processing capabilities. Bridgehead servers must compress and decompress replication data efficiently. The server with the slowest processor on your network would not be the best choice for the role of bridgehead server.

--> Configure multiple bridgehead servers for multiple partitions.

--> If a server that has been designated by the ISTG as a preferred bridgehead server fails, the ISTG will assign a new bridgehead server from the configured list. This assumes that you have configured more than one server in the list. It is, therefore, recommended that you configure multiple preferred bridgehead servers whenever possible.

The simple definition of Bridgehead Server is :

" Bridgehead Server is automatically designated by KCC as the contact point for transferring/exchanging  the directory information between sites. And KCC dynamically chooses a server from each site to handle the replication and to minimize the bandwidth usage during Intersite replication or communication". 

Guys I hope your clear about the Bridgehead Server, Let me know if you have any questions and comments or feedback in the below comments section... I will get back to you...