Planning external users with Two Domains and DirSync

Anyone planned to use two AD Domains for SharePoint External/Internal use ?

I mean, for an extranet site where both customers and internal users can login in, is that a good way to have :

• 1 AD Domain for internal users (already there)


• 1 AD Domain for external users (located in DMZ still works ?)


• 1 SharePoint Server that hosts our Intranet in Internal Domain


• 1 SP Server that hosts the extranet and in External domain

Then I would like to use DirSync to sync some attributes (I don't know which one atm), and permit internal users to login into the Extranet site.

DirSync would sync internal AD account to External one, and sync ID/PWD.

Is there any security problems ?