How can I setting DNS server?

I install angstrom in my BB.
and I set DNS server using Network Setup(Xwindow menu).
and I conform configuration in /etc/resolv.conf
cat /etc/resolv.conf
nameserver 168.126.63.1

but I reboot my bb. That configuration is removed( /etc/resolv.conf).
How can I fix my configuration?

Thanks.
Have a nice day...

Take a look at:
http://wiki.debian.org/NetworkConfiguration
http://www.linuxtogo.org/gowiki/AngstromManual

My first guess is that the DHCP client is running (udhcpc) and that could be erasing your /etc/resolv.conf.