Its very normal to have a scenario in which the user profile information in stored in directory service like Active Directory. Since personalization in sharepoint largely depends upon user profiles it becomes imperative to not only import the user information in AD into sharepoint as user profiles but also to run incremental imports to sync up user profiles with new information added into the Active directory.
As you know sharepoint integrates with Active directory and a user profile record gets created in sharepoint when an AD authenticated user first accesses a site. Assumption here is that the user already has adequate permissions on the site. As noted above incremental imports facilitate synchronizing user information stored in AD with the profile created in sharepoint.
The following steps need to be followed to configure import of user profiles from Active Directory -
Scenario-1 - All users are in the current domain.
1. Go to User Profile and Properties under Shared Services Administration.
2. Click on configure profile import link. Select current domain as the profile datasource.
3. Make sure default access account is specified and is valid.
4. Run full import or incremental report.
Scenario-2 - Users are scattered into multiple domains or other data sources.
1. Go to User Profile and Properties under shared services administration.
2. Click on Import New Connection. Add a new connection for each of the data sources where you users are located. Delete any unwanted connections that might already be there.
3. Configure the import as mentioned above and make sure that Custom source is selected.
4. Run the full import or incremental import.
