This is just an emple of a the interfaces file which holds the ifconfig information.

Location: /etc/network/interfaces

Static IP (example)
#######################
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 208.88.34.106
netmask 255.255.255.248
broadcast 208.88.34.111
network 208.88.34.104
gateway 208.88.34.110

#######################

DHCP (example)

#######################

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto eth1
iface eth1 inet dhcp

auto eth2
iface eth2 inet dhcp

auto ath0
iface ath0 inet dhcp

auto wlan0
iface wlan0 inet dhcp

########################