ad-server: use no dns-backend in AD-Server.

ad-server/tasks/main.yml

@@ -42,7 +42,7 @@
 # TODO: Evaluate if internal DNS-backend is powerful enough for usecase otherwise bind9 is needed
 
 - name: ensure domain is provisioned
-  shell: samba-tool domain provision --use-rfc2307 --domain={{ smb_domain }} --server-role=dc --host-name={{ ansible_hostname }} --realm={{ REALM }} --dns-backend=SAMBA_INTERNAL --adminpass={{ adminpass.password }}  2> /root/smb-provision.log
+  shell: samba-tool domain provision --use-rfc2307 --domain={{ smb_domain }} --server-role=dc --host-name={{ ansible_hostname }} --realm={{ REALM }} --dns-backend=None --adminpass={{ adminpass.password }}  2> /root/smb-provision.log
   when: domain_provisioned.stat.exists == False
   tags: 
     - ad-server