Active Directory Cookbook, 4th Edition

Chapter 12. Replication

Introduction

Replication is one of the most important and perhaps complex components of Active Directory. The infrastructure behind Active Directory replication, including the site topology, connection objects, and the KCC, was covered in Chapter 11. This chapter focuses strictly on some of the tasks and processes associated with replicating data and checking replication health. For an in-depth overview of how replication works in Active Directory, we suggest reading Active Directory, Fifth Edition by Brian Desmond et al. (O’Reilly).

Determining Whether Two Domain Controllers Are in Sync

Problem

You want to determine whether two domain controllers are in sync and you do not have objects to replicate to each other.

Solution

Using a command-line interface

By running the following command you can compare the up-to-dateness vector on DC1 and DC2:

> repadmin /showutdvec <DC1> <NamingContextDN>
> repadmin /showutdvec <DC2> <NamingContextDN>

Using PowerShell

By running the following command you can compare the up-to-dateness vector on a domain controller named DC1 and a domain controller named DC2:

Get-ADReplicationUpToDatenessVectorTable -Target DC1,DC2

Discussion

To determine whether two or more DCs are in sync from a replication standpoint, you need to compare their up-to-dateness vectors. Each domain controller stores what it thinks is the highest update sequence number (USN) for every DC that replicates a naming context. This is called the up-to-dateness vector. If you ...