DNS in Ubuntu 12.04

http://www.stgraber.org/2012/02/24/dns-in-ubuntu-12-04/

Any change manually done to /etc/resolv.conf will be lost

Resolvconf has a /etc/resolvconf/resolv.conf.d/ directory that can contain “base”, “head”, “original” and “tail” files. All in resolv.conf format.

• base: Used when no other data can be found 
• head: Used for the header of resolv.conf, can be used to ensure a DNS server is always the first one in the list 
• original: Just a backup of your resolv.conf at the time of resolvconf installation 
• tail: Any entry in tail is appended at the end of the resulting resolv.conf. In some cases, upgrading from a previous Ubuntu release, will make tail a symlink to original (when we think you manually modified resolv.conf in the past) 

“nm-tool” can be used to get information about your existing connections in Network Manager. It’s roughly the same data you’d get in the GUI “connection information”.

Alternatively, you can also read dnsmasq’s configuration from /run/nm-dns-dnsmasq.conf

sudo restart network-manager