only_from_default
Description:
If set to nm_ternary_true, NetworkManager attempts to get the hostname via DHCPv4/DHCPv6 or reverse DNS lookup on this device only when the device has the default route for the given address family (IPv4/IPv6).
If set to nm_ternary_false, the hostname can be set from this device even if it doesn't have the default route.
When set to nm_ternary_default, the value from global configuration is used. If the property doesn't have a value in the global configuration, NetworkManager assumes the value to be nm_ternary_false.