Error: The Knowledge Consistency Checker (KCC) has detected problems with the following directory partition

The other day I recieved the following alert from SCOM:

The Knowledge Consistency Checker (KCC) has detected problems with the following directory partition. Directory partition: CN=Configuration,DC=my,DC=domain,DC=com There is insufficient site connectivity information for the KCC to create a spanning tree replication topology. Or, one or more directory servers with this directory partition are unable to replicate the directory partition information. This is probably due to inaccessible directory servers. User Action Perform one of the following actions: - Publish sufficient site connectivity information so that the KCC can determine a route by which this directory partition can reach this site. This is the preferred option. - Add a Connection object to a directory service that contains the directory partition in this site from a directory service that contains the same directory partition in another site. If neither of the tasks correct this condition, see previous events logged by the KCC that identify the inaccessible directory servers.

The KCC automatically generates and maintains the replication topology within a site and between sites. You can disable the KCC within a site (intrasite) and between sites (intersite).

The KCC runs at regular intervals, adjusting the replication topology if any changes occur in Active Directory. Changes may include the addition of new DCs, or the creation of new sites. The KCC also simultaneously reviews the replication status of existing connections and determines if any are not working. If a connection is not working, the KCC automatically builds temporary connections to other available replication partners to ensure that replication continues.

You can verify the inbound replication topology with repadmin - this should also verify if there is any connectivity to that specific DC:

repadmin /kcc dc02.domain.com

To diagnose this error you should verify replication connecitvity between all of the domain controllers.

You should verify site connectivity (from one DC to another) from Sites and Services.

This issue commonly arrises when a branch site has lost connectivity or the DC on that specific site is down.