It's a blend of the two threads here:
https://communities.vmware.com/t5/Skyline-Health-Diagnostics-SHD/Name-Resolution-on-SHD-appliance/m-...
https://communities.vmware.com/t5/Skyline-Health-Diagnostics-SHD/How-do-I-change-the-DNS-settings-on...
Just add that Domain=xy.local to the /etc/systemd/network/*.network file and restart the systemd-resolved & systemd-networkd with the commands
systemctl restart systemd-networkd
systemctl restart systemd-resolved
Good Luck!
