Manually configure a network interface to get an IP from a DHCP server

Got an Ubuntu 13.10 machine with one network interface. Added another one to test internal networking. To make this new network interface get IP address from DHCP server, we need to modify /etc/network/interfaces, like:

auto eth1
iface eth1 inet dhcp

Reference(s):
https://help.ubuntu.com/10.04/serverguide/network-configuration.html

Keywords:
network interface IP Ubuntu