DNS Problem with two Network cards

On a server or PC with two network cards running Ubuntu Linux, you are inevitably tempted to hardcode your IP addresses by editing /etc/networking/interfaces. Logically you may draw the conclusion that both devices should be configured with the same routing information like this:



auto lo
iface lo inet loopback


# This is a list of hotpluggable network interfaces.
# They will be activated automatically by the hotplug subsystem.
mapping hotplug
script grep
map eth0

# The primary network interface
auto eth0
iface eth0 inet static
address 192.168.0.8
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255
gateway 192.168.0.1

auto eth1
iface eth1 inet static
address 192.168.0.9
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255
gateway 192.168.0.1



this is actually incorrect and will cause two symptoms. When you run /etc/init.d/networking restart you get this response:


RTNETLINK answers: no such process


Your internal network will work ok and you'll be able to access the system but you will not be able to get to the outside network and a ping to google.com will come back with unknown host. 


The solution is to remove the second gateway listing (highlighted in red). You only need one. Run /etc/init.d/networking restart and you should be good to go.