Change a server's hostname in CentOS

Change a server’s hostname

Using a text editor, open the server’s /etc/sysconfig/network file.

# sudo nano /etc/sysconfig/network

Modify the HOSTNAME= value to match your FQDN hostname. 

HOSTNAME=myserver.domain.com 

For internal networking, change the host that is associated with the
main IP address for your server (found at /etc/hosts).

127.0.0.1      localhost localhost.localdomain

 123.45.67.89   hostname.domain.com   hostname

 ~

 ~

 ~

 ~

 -- INSERT --                         2,43-57    ALL 

Run the hostname command. This command lets you change the
hostname on the server that the command line remembers, but it does
not actively update all programs that are running under the
old hostname.

 [root@defiant ~]# hostname hostname.domain.com

 [root@defiant ~]# hostname

 hostname.domain.com

 [root@defiant ~]#  

Restart networking on your server to ensure that changes will persist on restart.

 /etc/init.d/network restart