Overview#Knowledge Consistency Checker (KCC) is a Microsoft Active Directory component that automatically generates and maintains the intra-site and inter-site replication topology.
Knowledge Consistency Checker is present on every Domain Controller and automatically generates the "most efficient" replication topology at a default interval of every 15 minutes. Knowledge Consistency Checker creates connection objects that link Domain Controllers into a common replication topology. The Knowledge Consistency Checker has two components:
- intrasite KCC which deals with replication within the Active Directory Site
- Intersite Topology Generator (ISTG), which establishes connection objects between sites (only one Domain Controller in each Active Directory Site holds the ISTG role at any given time).
Knowledge Consistency Checker in a Active Directory Site with many Domain Controllers, a ring topology can quickly violate the no-more-than three-hops rule, so the KCC will generate shortcuts across the ring to reduce the number of hops between Domain Controllers.