dns field sets a list of DNS servers for the app to use. At most four servers can be defined, and each much be a valid IPv4 address. It is usually not necessary to define DNS servers when using DHCP for your network configuration, since many DHCP servers provide their own list of DNS servers to clients.
FIELD dns PATH system.dns PARENT system TYPE String DEFAULT 
[system] dns = ["18.104.22.168", "22.214.171.124"]