# hostname zafira
Then search through /etc, for example, for occurances of the old name, just in case:
# grep -r inco /etc
Typically you will find the hostname hardwired in /etc/hosts, /etc/mailname, /etc/motd, and various apache, ppp, ssh, and exim files, depending on your setup. These can probably be edited by hand to replace the host name.
Users have reported making such changes without problem. Some people have reported problems rebooting after making some of these changes so be careful!