April 05, 2004, 12:00 AM — 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
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 server1.domain.com,
you would issue the following command:
repadmin /kcc server1.domain.com
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: