I have Server 2012 as Domain controller and DNS server.
Now if I have a machine joined to the domain, they get all servers names defined in dns zone.
I have a Windows 7 client which is not joined to the domain, but I want it to get the IP of the DNS servers.
I tried manually putting the IP 192.168.0.100
in the DNS of the network adapter, but it does not get the IP of the DNS servers.
When not a part of the domain, you need to use the FQDN of the host you are trying to resolve. Example:
A server named app01 on domain.lab with ip 192.168.0.69 being pinged from a machine on the same network, but not in the domain.
ping app01 - host cannot be resolved
ping app01.domain.lab - Reply from 192.168.0.69: time=blah blah blah
If you want a non-domain joined computer to resolve internal names, you should be putting the domain controller (which has DNS on it) as the DNS server and setting the DNS prefix to whatever your domain name is. Even computers not on the domain will still be able to work with the DNS server.
What won't work is other computers resolving the name of the non-joined machine since it won't be in DNS, but that wasn't your requirement.