In Salesforce, there is an option to create local users [Setup -> Manage Users -> Users -> New User]. In addition, there is an option to map users from a domain (using Identity connect). For each user, I want to be able to determine if he was created locally or mapped from Active Directory. It will be nice if I'll get the specific domain for each domain user (in case that there are more then one domain in organization).
You can check the Federation Identifier field on the User Record .
The Federation ID User Field can only be accessed and edited if a user has the "Manage Users" permission granted via Profile or Permission Set. The "Manage Users" permission requires that "Reset User Passwords and Unlock Users" and "View Setup and Configuration" permissions be enabled as well.
When a user is created from AD ,I am sure you might be having an external Id field on the user record you can look for that as well.