The value of sysDNSAddressResolvePref specifies how the DNS
client will request for address resolution.
ipv4-only: The DNS client will only try to resolve a domain name
into an ipv4 address.
ipv6-first: the DNS client will first try to relsove the
domain name in to ipv6 address. If no ipv6 address
is available it will try to resolve the domain name
into an ipv4 address.