ares_set_local_dev - Bind to a specific network device when creating sockets.
void ares_set_local_dev(ares_channel channel, const char* local_dev_name)
function causes all future sockets to be bound to
this device with SO_BINDTODEVICE. This forces communications to go over a
certain interface, which can be useful on multi-homed machines. This option is
only supported on Linux, and root privileges are required for the option to
work. If SO_BINDTODEVICE is not supported or the setsocktop call fails
(probably because of permissions), the error is silently ignored.
This function was added in c-ares 1.7.4