Ubuntu- DNS - setting it to static and dynamic

In case of static

cat /etc/network/interfaces

# The loopback network interface  
auto lo  
iface lo inet loopback  


# The primary network interface  
auto eth0 
iface eth0 inet static  
address 192.168.1.58  
gateway 192.168.1.1
network 192.168.1.0  
broadcast 192.168.1.255
dns-nameservers 66.212.63.228 66.212.48.10  

Setting it to dhcp

 iface eth0 inet dhcp