I also Would like more info on this as well....
I am seeing that LDAP /LDAPS configured integrations to Active Directory Domains do NOT obey the preferred domain controllers that are specified in AD Sites and servers for the particular source IP address that made the Authentication request.
In my example we have 25 domain controllers in different locations. All the Windows devices using Integrated Windows Authentication will choose a domain controller based on the preferred configuration for the IP of the device as specified in sites and services.
Any LDAP /LDAPS configured applicaiton with do authentication to any of the 25 random domain controllers basically by looking up the domain name. Since we have Domain Controllers in AWS and Azure and 3 different data Centers this sometimes makes for a slower login/authentication time depending on what DC is used.
I realize we could specifically specify a specific domain controller but that eliminates and redundancy of using other DC's and makes migration of DC's very complicated.