Editing Active Directory (section)

==Implementation==
Generally, a network utilizing Active Directory has more than one licensed Windows server computer. Backup and restore of Active Directory are possible for a network with a single domain controller.<ref>{{Cite web |title=Active Directory Backup and Restore |url=https://technet.microsoft.com/en-us/library/bb727048.aspx |access-date=5 February 2014 |work=[[Microsoft TechNet|TechNet]] |date=9 December 2009 |publisher=[[Microsoft]]}}</ref> However, Microsoft recommends more than one domain controller to provide automatic [[failover]] protection of the directory.<ref>{{cite web |title=AD DS: All domains should have at least two functioning domain controllers for redundancy |url=https://technet.microsoft.com/en-us/library/dd378865%28v=ws.10%29.aspx |access-date=5 February 2014 |work=[[Microsoft TechNet|TechNet]] |publisher=[[Microsoft]]}}</ref> Domain controllers are ideally single-purpose for directory operations only and should not run any other software or role.<ref>{{cite web |last=Posey |first=Brien |date=23 August 2010 |title=10 tips for effective Active Directory design |url=http://www.techrepublic.com/blog/10-things/10-tips-for-effective-active-directory-design |access-date=5 February 2014 |work=[[TechRepublic]] |publisher=[[CBS Interactive]] |quote=Whenever possible, your domain controllers should run on dedicated servers (physical or virtual).}}</ref>

Since certain Microsoft products, like SQL Server<ref>{{Cite web |date=7 January 2013 |title=You may encounter problems when installing SQL Server on a domain controller (Revision 3.0) |url=http://support.microsoft.com/kb/2032911 |access-date=5 February 2014 |work=Support |publisher=[[Microsoft]]}}</ref><ref>{{Cite web |last=Degremont |first=Michel |date=30 June 2011 |title=Can I install SQL Server on a domain controller? |url=http://blogs.technet.com/b/mdegre/archive/2011/07/01/can-i-install-sql-server-on-a-domain-controller.aspx |access-date=5 February 2014 |work=Microsoft SQL Server blog |quote=For security and performance reasons, we recommend that you do not install a standalone SQL Server on a domain controller.}}</ref> and Exchange,<ref>{{Cite web |date=22 March 2013 |title=Installing Exchange on a domain controller is not recommended |url=https://technet.microsoft.com/en-us/library/ms.exch.setupreadiness.warninginstallexchangerolesondomaincontroller%28v=exchg.150%29.aspx |access-date=5 February 2014 |work=[[Microsoft TechNet|TechNet]] |publisher=[[Microsoft]]}}</ref> can interfere with the operation of a domain controller, isolation of these products on additional Windows servers is advised. Combining them can complicate the configuration and troubleshooting of the domain controller or the other installed software more complex.<ref>{{Cite web |title=Security Considerations for a SQL Server Installation |url=https://technet.microsoft.com/en-us/library/ms144228.aspx |access-date=5 February 2014 |work=[[Microsoft TechNet|TechNet]] |publisher=[[Microsoft]] |quote=After SQL Server is installed on a computer, you cannot change the computer from a domain controller to a domain member. You must uninstall SQL Server before you change the host computer to a domain member.}}</ref> If planning to implement Active Directory, a business should purchase multiple Windows server licenses to have at least two separate domain controllers. Administrators should consider additional domain controllers for performance or redundancy and individual servers for tasks like file storage, Exchange, and SQL Server<ref>{{Cite web |title=Exchange Server Analyzer |url=https://technet.microsoft.com/en-us/library/aa997379%28v=exchg.80%29.aspx |access-date=5 February 2014 |work=[[Microsoft TechNet|TechNet]] |publisher=[[Microsoft]] |quote=Running SQL Server on the same computer as a production Exchange mailbox server is not recommended.}}</ref> since this will guarantee that all server roles are adequately supported.

One way to lower the physical hardware costs is by using [[virtualization]]. However, for proper failover protection, Microsoft recommends not running multiple virtualized domain controllers on the same physical hardware.<ref>{{Cite web |quote=You should attempt to avoid creating potential single points of failure when you plan your virtual domain controller deployment.frank |title=Running Domain Controllers in Hyper-V |work=[[Microsoft TechNet|TechNet]] |publisher=[[Microsoft]] |url=https://technet.microsoft.com/en-us/library/d2cae85b-41ac-497f-8cd1-5fbaa6740ffe%28v=ws.10%29#bkmk1_planning_to_virtualize_domain_controllers |at=Planning to Virtualize Domain Controllers |access-date=5 February 2014}}</ref>