To change the hostname of a linux distribution you can either change the hostname on-the-fly, but it does not restore it after a reboot. To change the hostname on-the-fly you can do
echo "your new hostname" > /proc/sys/kernel/hostname
on a ubuntu/debian system to alter the hostname after a reboot you can alter the
file, if you cannot find the hostname file there, you can search for the file within the /etc directory by
grep -R "your hostname" /etc
it will display a few files, but you should find out where your hostname is set, normally either within /etc/sysconfig or /etc/network directories.