What are the basic reasons which defines not to have AD DC on VM's ?

You can run a DC on a VM, as long as you still have a physical machine running as a DC also. The main reason from my understadning, is if you have all your DC's running as VM's, and the physical machine goes down, you lose all your DC's. Also, when the physical machine comes up, there is no way for it to authenticate to the domain, seeing that the VM's running the DC's are not fully loaded until the physical machine is up and running.

this is just my opinion, imo people dont recommend it as you can do things with a vm easily which are not supported with a dc, like taking snapshots (restoring them can cause havoc with your active directory). technically, you can do that with a physical dc as well (3rd party tools like acronis and so on), so I don't really consider them virtualisation problems. all in all, again my opinion, unless you have a cluster running, which requires a dc to operate (in that scenario id use one phyiscal dc to have the dc running when you start up the cluster), imo it is perfectly ok to have your dc(s) as vm. you can read the blog (and the link in it about consideratiosn when deploying virtual dc's) for more infos http://blogs.technet.com/b/askds/archive/2010/06/10/how-to-virtualize-active-directory-domain-controllers-part-1.aspx

You can run DC in virtualised environment However, snapshot should NOT be applied to prevent USN Rollback. More on USNrollback :http://utools.com/help/UsnRollback.asp I do not represent the organisation I work for, all the opinions expressed here are my own. This posting is provided "AS IS" with no warranties or guarantees and confers no rights.

What are the basic reasons which defines not to have AD DC on VM's ? Hello, where did you have this information from? This complete incorrect and Microsoft supports DC VMs.Best regards Meinolf Weber MVP, MCP, MCTS Microsoft MVP - Directory Services My Blog: http://msmvps.com/blogs/mweber/ Disclaimer: This posting is provided AS IS with no warranties or guarantees and confers no rights.

Hiya, 1: If host server is domain member, there will be a problem contacting a DC if your domain is only virutal. I wont be available until after the host starts up. The previous posts states some good examples on things that could go wrong in operation of the virtual DC.:)

Hiya, 1: If host server is domain member, there will be a problem contacting a DC if your running virtual only domain controllers. It wont be available until after the host starts up. The previous posts states some good examples on things that could go wrong in operation of the virtual DC.:)