Configuring DHCP address for your network card

sudo vi /etc/network/interfaces

# The primary network interface – use DHCP to find our address
auto eth0
iface eth0 inet dhcp

Configuring Static IP address for your network card

sudo vi /etc/network/interfaces

# The primary network interface

auto eth0
iface eth0 inet static
address 192.168.3.90
gateway 192.168.3.1
netmask 255.255.255.0
network 192.168.3.0
broadcast 192.168.3.255

Setting up Second IP address or Virtual IP address in Ubuntu

sudo vi /etc/network/interfaces

auto eth0:1
iface eth0:1 inet static
address 192.168.1.60
netmask 255.255.255.0
network x.x.x.x
broadcast x.x.x.x
gateway x.x.x.x

 Setting up DNS

sudo vi /etc/resolv.conf

enter the following details

search test.com
nameserver 192.168.3.2

หลังจากเปลี่ยนแล้วก็ให้ทำการ Save ให้เสร็จ แล้วก็ Restart Network โดยใช้คำสั่งด้านล่างนี้เลย

sudo /etc/init.d/networking restart