There are two areas you can change to ensure ARS is using the closest domain controller:
- DirSync Server for each managed domain:
- ARS MMC | Configuration | Server Configuration | Managed Domains | Property of your Domain | DirSync Server tab.
- From here you can change the server that ARS talks with for all active directory updates. If the server that is currently selected is not the closest DC, you can switch it here.
- On a per-client basis you can change your Operational Domain Controller:
- To do this, from the ARS MMC | Active Directory | Domain Name.
- Right-click your domain name and choose ALL TASKS | Change Operational DC
This allows you to set on a per-connected client setting of what domain controller your server speaks with. This can be helpful in large environments with many DC's and long replication delays.