I have a question about the domain controller discovery process if we have Active directory Load balancers in the environment and how it's going to behave in this scenario.
In one of the customer environments, active directory load balancers are used and the traffic will be redirected to correct regions domain controllers. In this case, the load balancer's IP addresses are added as preferred DC's. The added load balancers IP's are not Domain controllers so the CIFS discovered servers will show as unavailable and as per the theory of domain controller discovery, the available DC's will be selected based on query process/procedure. In this scenario, does adding the load balancer IPs to prefdc will redirect the requests to the correct domain controller? From my knowledge, I don't think so, as it won't find the correct SRV record as the load balancers are not of that type (Correct SRV records. )
What is the ideal method to use if we have load balancers (Active directory)
Interesting question, and I agree with your comments that it will not work (wondering how SPN translation could go haywire). Config on Ontap, automatically discovers domain controllers through DNS. Optionally, you can add one or more domain controllers to the list of preferred domain controllers for a specific domain that's it. I don't know if any other non-Microsoft platform can do that without additional layer of complexity.
Ontap has DNS load balancing but then this is different. Domain Name System (DNS) load balancing is a method by which administrators can be sure that clients accessing SVM Data LIFs are accessing them in a manner that does not overload individual LIFs.