yun selected ip interface

Hi, if I have both interaces (wifi and ethernet) configured to be client or server what is used to route my packet? The client constructor does not specify if I want to create a client that use the wifi or the ethernt.

Thanks in advance

differential by ip address of the wifi or the ethernt.

If I have to contact the yun ok but if it's the yun that send packet to the internet which interface would it use?

root@Arduino:/mnt/sda1# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         UG    0      0        0 eth1     *        U     10     0        0 eth1   *        U     0      0        0 wlan0

if both ethernet and wifi connected to internet , It will go for low-cost routes (metric) . The wifi net is preferable since it has less metric.