2.6. SSSD Clients and Active Directory DNS Site Autodiscovery

Active Directory forests can be very large, with numerous different domain controllers, domains and subdomains, and physical sites. Active Directory uses DNS records to identify a physical location for its domain controllers. This enables clients to first connect to the domain controller that is geographically closest, which increases client performance.
By default, SSSD clients use the autodiscovery to connect to the closest domain controller. To override the autodiscovery, specify the AD site to which you want the client to connect by using the ad_site option in the /etc/sssd/sssd.conf file.

Additional Resources