taming information technology at small and medium enterprises

Wednesday, August 14, 2013

Active Directory Replication Delay Sucks. Here's How I Unsuck It

Have you ever made a change to Group Policy or an Active Directory User account, then  you test your change, only to discover it isn't working?  This annoyance can be caused by replication delays between your domain controllers.

troubleshooting active directory sites and services
The only time I've used the actual Visio symbol for an AD site.
You can force a replication using the Sites and Services console GUI, but that's a nightmare of clicking and if you find yourself doing it more than once a week, there's a much easier way:  Powershell.

Here's my script to force replication between all domain controllers.

Write-Host "Beginning replication"
# Get domain controller list,

# do a foreach-object to replicate
Get-ADDomainController -filter * | % {
  Write-Host "Replicating $($_.Name)"
   # KCC recalculation
   $null = repadmin /kcc $_.Name
   # Replicatiion
   $null = repadmin /syncall /A /e $_.Name

Write-Host "Completed replication"

Now look, dude:  Always review scripts for errors and test them in a non production environment.  This script works well on the smaller networks I typically work on--less than 5 sites with 2 domain controllers per site, and less than 200 users might be typical.  With large or busy Active Directory installations it may not be desirable to force a replication during production hours.

Regarding AD replication.  Learn this before you screw around with replication settings:

Active Directory Replication Model Technical Reference

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