I have always heard never virtualize your domain controller is this good practice or old school? I think it is ok to virtualize a DC in Server 2012R2 from what I have read but I am wanting to get some advice. Most of our customers are only 5-25 users with one server. I would like to use one host with 2 vm's one of them the DC and the other an app and file server. Is this a good practice?