I will go trough basic steps for installing Active Directory on Windows Server 2012 R2. I will not go trough network or routing configuration. I assume network is already set up. I will also not go into all available options during install. I will just go trough steps to install Active Directory Services. I will use fresh installation of Windows Server 2012 R2.
Open ‘Server Manager’ and open ‘Local Server’. On this screen set ‘Computer name’, ‘IP address’, ‘Time zone and time’. You can also enable ‘Remote Desktop’, disable ‘IE Enhanced Security configuration’ and set ‘Windows update’ settings.
When server is restarted open ‘Server Manager’ and open ‘Local Server’. From here you can also change IP address. Active Directory server should have fixed IP address. Change IP to static.
Right click on you network adapter and choose (with left click) ‘Properties’
If you closed ‘Add Roles and Features Wizard’ skip the next step.
You can select ‘functional level of fores’ and you need to enter ‘Directory Services Restore Mode password’. This is NOT password that you will use to log on to new domain. This password you will use if something goes wrong with your Active Directory.
When you need to repair your Active Directory you will have to start Windows Active Directory server in ‘Directory Services Repair Mode’ and you will use this password to log in. Hopefully you will never have to use it. But keep this password in case you need it.
Domain Administrator password will be same as Administrator password before you promoted server to Domain Controller. Domain Controller does not have ‘Local Security’ and does not have ‘Local Administrator’ account. On domain controller you can log on only using Domain Administrators credentials.
When you check TCP/IP v4 settings you will notice that Preferred DNS is set to 127.0.0.1. Domain controller will query DNS server on itself that was installed during domain controller promotion. DNS is ‘heart’ of Microsoft Active Directory Services. Do not change this settings.
If you check forwarder settings in DNS server settings you will notice that forwarder is set to DNS server that was preferred DNS server before domain controller promotion.
Enjoy your new Domain controller.