To retrieve a space-delimited list IP address(es) of DNS server(s), up to three, that are currently in use by the device. The values to be used are a combination of addresses received from DHCPv4, DHCPv6, and user-set values using the following rules:
At least one spot will be allocated to any enabled IP version.
IPv4 addresses will take at least two slots if at least two IPv4 addresses are provided.
User-set values will be included if static/permanent addresses are used.