When we install ubuntu server and set DNS addresses (ex. 126.96.36.199), the event that the DNS setting is not reflected in netplan yaml file (/etc/netplan/*.yaml) may occur.
We finded that the reason is related to the source code of the network package 'netcfg'.
In the function 'nc_wi_netplan_write_nameservers' of write_interface.c of netcfg-1.142ubuntu5(netcfg package source code directory), the nameservers are not written in the netplan yaml file if domain name is empty string.
We hope that the nameservers are written even if domain name is empty string.
Please check the bug.