# ls -ld /etc/resolv.conf
lrwxrwxrwx 1 root root 32 Nov 22  2017 /etc/resolv.conf -> /run/systemd/resolve/resolv.conf
# systemctl is-enabled systemd-resolved
enabled
# systemctl is-enabled systemd-networkd
enabled

===== /etc/systemd/network/vpn_vpn.network
[Match]
Name=vpn_vpn

[Network]
DHCP=ipv4
LinkLocalAddressing=no
DefaultRouteOnDevice=no
DNSDefaultRoute=no

[DHCPv4]
UseDomains=yes
UseHostname=no
UseRoutes=no

===== /etc/nsswitch.conf
# Name Service Switch configuration file.
# See nsswitch.conf(5) for details.

passwd: files systemd
group: files systemd
shadow: files

publickey: files

hosts: files mymachines myhostname resolve [!UNAVAIL=return] dns
networks: files

protocols: files
services: files
ethers: files
rpc: files

netgroup: files