No, I Will Not Fix Your #@$!! Computer → Dev, Test, Prod Enviroment

How do most of you that are in an AD environment have your Dev, Test, and Prod Domains setup? Are they part of a single forest, with child domains, or all separate domains?

One forest, separate domains.

Completely separate forests and subnets.

Makes it easy to keep it away from the production environment in the event we have to test something that might be icky.