Hi yangnigon,
as these are general DNS and AD questions, I would start to check for example here:
- https://en.wikipedia.org/wiki/Domain_Name_System
- https://en.wikipedia.org/wiki/Active_Directory
BSM / APM only uses DNS for name resolution, and AD in case it has been configured for LDAP authentication,
but all the operation, the how, where and why is usually provided and supported by the OS, network and infrastructure people.
Greetings
Siggi