If your PC has 2 connections: wire and wireless where the data will go

It will go to wire first then wireless after.
It seems to me when connect to wireless router and wire to another PC. The dhclient will write into resolv.conf with the info of nameserver and domain of the wire network. Therefore, the data will flow into wire.
dmesg:

ADDRCONF(NETDEV_UP): eth0: link is not ready
ADDRCONF(NETDEV_UP): wlan0: link is not ready
Mobile IPv6
wlan0: Initial auth_alg=0
wlan0: authenticate with AP 00:16:b6:c0:0d:e9
wlan0: RX authentication from 00:16:b6:c0:0d:e9 (alg=0 transaction=2 status=0)
wlan0: authenticated
wlan0: associate with AP 00:16:b6:c0:0d:e9
wlan0: RX AssocResp from 00:16:b6:c0:0d:e9 (capab=0x401 status=0 aid=2)
wlan0: associated
ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
wlan0: no IPv6 routers present
wlan0: no IPv6 routers present
r8169: eth0: link up
ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
eth0: no IPv6 routers present
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