So let’s flesh out a bit why we need one domain controller, one member server for Exchange and one member server for SharePoint.
First let’s lay the foundations of what CANNOT/SHOULD NOT/and is really and truly not recommended to be installed on a domain controller.
First up is SharePoint 2013:
Certain Microsoft SharePoint Server 2013 installation scenarios are not supported:
“You install SharePoint Server 2013 on a domain controller. This scenario is supported only for development configurations and not for production configurations.”
Next up is Exchange…which other than on SBS isn’t supported on a Domain controller:
Exchange resident on domain controller that is not a global catalog server:
And specifically : http://technet.microsoft.com/en-us/library/aa996719.aspx
Installing Exchange 2013 on directory servers
“For security and performance reasons, we recommend that you install Exchange 2013 only on member servers and not on Active Directory directory servers. However, you can’t run DCPromo on a computer running Exchange 2013. After Exchange 2013 is installed, changing its role from a member server to a directory server, or vice versa, isn’t supported.”
So now that we can’t put SharePoint or Exchange on a domain controller, what if we put SharePoint and Exchange together on the same server?
“Please do not install Exchange Server 2010 together with Sharepoint 2010 on the same server. We always recommend to only host Exchange Server roles on one machine.”
Also note that in the SharePoint 2013 planning docs, at no point in time do they recommend that you install Exchange on your SharePoint server – see Configure outgoing email for a SharePoint 2013 farm:
The last (and as far as I can tell only) time Microsoft actually put forth that they’d support SharePoint and Exchange on the same server was back in the 2003 era (see http://office.microsoft.com/en-us/windows-sharepoint-services-it/coexistence-and-interoperability-guide-for-sharepoint-products-and-technologies-HA001160777.aspx )