Contacting a domain controller in Active Directory is done through DNS lookup. Several DNS SRV records are used to find domain controllers in a site. If multiple domain controllers are present in the same site, the client will arbitrarily select one, based on the contents of those records.

By default, the selection is random, and all DCs have an equal change of being picked. The inherit properties of SRV-records allow for this behaviour to be influenced, by changing the weight and priority of those records. This enables fine-tuning and configuration of which DC to favour or even exclude. By default, all SRV records (thus, all DCs) have their weight and priority set to 0.

The weight defines  ...