In the previous versions of Horizon DaaS, you had to change DNS via the interfaces file and the resolv.conf file. Since VMware upgraded the OS of the Horizon DaaS appliances to Ubuntu 18.04 LTS these changes must be done via netplan. Below I will explain how to use netplan.
How to add an additional DNS server
First, we make a connection to one of the appliances via SSH. In this example, I will use Putty but feel free to use any SSH tool you prefer.
Use the command ls to show the configuration file in the /etc/netplan directory.
Edit the config file shown in the netplan directory by using the following command.
sudo nano /etc/netplan/50-cloud-init.yaml
Locate the addresses of the nameservers and add the DNS server.
Use the following commands to save the config file and exit nano.
CTRL + O to save CTRL + X to exit
Now we added the DNS server and we will need to make it active. Apply the settings by using the command.
sudo netplan apply
I think using netplan is easier and more straightforward that the old way. Hope this is/was helpful to you.