Active Directory

Last week we talked about sites and mapping your underlying network

topology into Active Directory. This week, we look at the Knowledge

Consistency Checker (KCC).

The KCC is a built-in service that runs on all Domain Controllers (DCs)

and automatically establishes connections between individual machines in

the same site. These "connections" are known as "connection objects".

An administrator may establish additional connection objects or remove

connection objects as well. At any point where replication within a

site becomes impossible or has a single point of failure, the KCC will

step in and establish as many new connection objects as necessary in an

attempt to resume the replication process.

The KCC creates connections dynamically between the domain controllers

and triggers replication. As the number of domain controllers

increases, replication consumes more and more network bandwidth. The KCC

attempts to balance the need for consistency against bandwidth

limitations. This is achieved by allowing no more than three

connections from any one DC. Additionally, the KCC automatically

maintains domain.

Just like in Windows NT 4.0, you can force replication. To do this, you

must manually force the KCC to run immediately by using a tool from the

Windows 2000 and Windows Server 2003 Support Tools called the

Replication Diagnostics Tool (Repadmin.exe).

For example, to force the KCC on the server named,

you would issue the following command:

repadmin /kcc

As you can see, the KCC is something that does a lot of work for you and

requires minimal interaction on the part of the administrator.

Join me next week when we continue our discussion on sites and


Catch up on the entire series here:

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