While CentraSite is running, there is always exactly one default user repository. When you install CentraSite, the default user repository is set to the internal text file. You can change the default to any other user repository for which an authentication configuration exists.

Users who are registered in the default user repository can omit the domain name when they log in. For example, if the domain Headquarters is the default domain and it contains a user whose user name is JSmith, then this user can log in as JSmith instead of Headquarters\JSmith. Users who are not registered in the default user repository must always use the format <DomainName>\<UserName> to log in.