VPN Redirection based on specific domain and IP

Question

I have a VPN connection on my mac and I try to redirect (1) only some IP range and (2) domain throw VPN connection.

1. I achieved to redirect all IP range from 192.168.11.0/24 through VPN by creating a file /etc/ppp/ip-up and write it :

   #!/bin/sh
   /sbin/route add -net 192.168.11.0/24 -interface ppp0
   

2. For the redirection of all hostname from a domain (ie. *.domain) to the VPN, I tried to define the DNS Name Server address in the parameters of the VPN connection but it doesn't work (cf. picture).

Is there another way to (a) redirect all *.domain to the VPN or (b) use firstly the remote DNS server ?

Many thanks