The loopback network interface

auto lo iface lo inet loopback

The primary network interface

auto eth0 iface eth0 inet static address 172.16.32.3 netmask 255.255.0.0 network 172.16.0.0 broadcast 172.16.255.255 gateway 172.16.0.10 dns-nameservers 172.16.240.20 172.16.0.21