Replication and FSMO roles: keeping domain controllers in agreement
Sites, subnets and site links; how the KCC builds replication; checking health with repadmin and dcdiag; the five operations master (FSMO) roles and what breaks when one is down; transferring versus seizing; tombstone lifetime, lingering objects and USN rollback.
- Level
- Advanced
- Length
- About 60 minutes
- Contents
- 3 lessons · final exam
- Status
- Published · updated 1 Oct 2026
Skills you'll practise
- Explain how sites, subnets, site links and the KCC shape intrasite and intersite replication
- Check replication health with repadmin /replsummary, repadmin /showrepl and dcdiag and interpret the results
- Identify the five FSMO roles, their scope and the impact when a role holder is unavailable
- Choose between transferring and seizing a role, and state what must happen to a former holder after a seizure
- Recognize lingering objects and USN rollback and the conditions that cause them
Course outline
- 1.Sites, site links and how replication flowsLesson · 18 min
- 2.Checking replication healthLesson · 16 min
- 3.FSMO roles: transfer, seize and clean upLesson · 16 min
- 4.Replication and FSMO roles: keeping domain controllers in agreement: knowledge checkKnowledge check · 14 questions
- 5.The domain controller that held the roles is goneScenario
- 6.Final exam8 questions · passing it completes the course, so people who already know the material can test out
Sources it draws on
The lessons and questions are written from these references, so learners can go back to the original.
- Microsoft Learn: Active Directory replication concepts
- Microsoft Learn: Determining the interval (site link replication interval)
- Microsoft Learn: Diagnose Active Directory replication failures
- Microsoft Learn: Repadmin /replsummary (archived command reference)
- Microsoft Learn: dcdiag
- Microsoft Learn: Planning operations master role placement
- Microsoft Learn: Transfer or seize operation master roles
- Microsoft Learn: Move-ADDirectoryServerOperationMasterRole
- Microsoft Learn: Lingering objects in an AD DS forest
- Microsoft Learn: Safely virtualizing Active Directory Domain Services (USN rollback and VM-GenerationID)
- Microsoft Learn: How to detect and recover from a USN rollback
See it with your own jobs and topics
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