Como configurar um IP primário no Windows Server 2012

Primário:

netsh int ipv4 add address <Interface Name> <ip address> <subnetmask>

Secundários:

netsh int ipv4 add address <Interface Name> <ip address> <subnetmask> skipassource=true

Exemplo:

netsh int ipv4 add address "WAN" 1.1.1.1 255.255.255.0
netsh int ipv4 add address "WAN" 1.1.1.2 255.255.255.0 skipassource=true
netsh int ipv4 add address "WAN" 1.1.1.3 255.255.255.0 skipassource=true
netsh int ipv4 add address "WAN" 1.1.1.4 255.255.255.0 skipassource=true

Referência: http://www.securahosting.com/2013/06/12/how-to-set-a-primary-ip-address-on-windows-server-2012/