How to downgrade Windows server2012 Domain Servers

Recently set up a Windows domain server in a new network environment, ready to establish a master, standby two domain servers. The WINDOWS2012R2 is installed on a new server and the DC service is configured. The domain and forest levels are set to the WINDOWS2012R2 level. When doing a secondary domain, an old server is used, and windows2012 is installed. When configuring this DC domain service, it is found that the domain and forest levels are incompatible and cannot be joined. After searching the internet, it was found that the domain and forest level of DCS after Windows server2008 could be degraded, just using PowerShell operation and no graphical interface.

In order to prevent forgetting, the special record is as follows:

1, first open the PowerShell command line interface, import the ad Management module, command for Import-module-name ActiveDirectory

2, check the forest level of AD, display as WINDOWS2012R2, command for Get-adforest | Format-table Name, Forestmode

3. Demote the corresponding forest and domain test.com to the windows2012 level, command set-adforestmode–identity "test.com" –forestmode windows2012forest and

Set-addomainmode–identity "test.com" –domainmode Windows2012domain

4, then use the command to detect whether the downgrade was successful. Command for Get-adforest | Format-table Name, Forestmode, and Get-addomain | Format-table Name, Domainmode