CentOS 7 supports three class of Host Names:

Static – The static host name is traditional host which can be chosen by the user and is stored in /etc/hostname file.

Transient – The transient host name is maintained by kernel and can be changed by DHCP and mDNS.

Pretty – It is a free form UTF -8 host name for the presentation to the user.

HostName can be,

• 64 character in a length
• Recommend to have FQDN
• Consists of a-z,A-Z, 0-9, “-”, “_” and “.” only

How to Change:

Before changing the host name, lets check the current host name.

[root@localhost ~]# hostname
localhost.localdomain

1. nmtui tool:

NetworkManaget tool is used to set the static host name in /etc/hostname file.

Set the host name.

restart the hostnamed to force the hostnamectl to notice the change in static host name.

[root@localhost ~]# systemctl restart systemd-hostnamed

You can verify the change in host name.

[root@server ~]# hostname
server.itzgeek.com
[root@server ~]# cat /etc/hostname
server.itzgeek.com
[root@server ~]# cat /etc/sysconfig/network
# Created by anaconda
HOSTNAME=server.itzgeek.com

2. hostnamectl:

hostnamectl is used to change the host name, with this tool we can change all the three class of host name; here we look only static host name.

Check the current host name.

[root@server ~]# hostnamectl status

Static hostname: server.itzgeek.com
Icon name: computer-vm
Chassis: vm
Machine ID: 565ea8b749544aca9d5563308f9e4bc2
Boot ID: 5c979d9b5f754df8b75a4e3aeabf2bad
Virtualization: vmware
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 3.10.0-123.el7.x86_64
Architecture: x86_64

Set the hostname.

[root@server ~]# hostnamectl set-hostname client.itzgeek.com

Check the host name again (Close the session and open new session using putty or console)

[root@client ~]# hostnamectl status

Static hostname: client.itzgeek.com
Icon name: computer-vm
Chassis: vm
Machine ID: 565ea8b749544aca9d5563308f9e4bc2
Boot ID: 5c979d9b5f754df8b75a4e3aeabf2bad
Virtualization: vmware
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 3.10.0-123.el7.x86_64
Architecture: x86_64

If you use this command, you do not require to notify the change in host name. Close the current session and re launch the terminal.

3. nmcli tool:

It can be used to query and setup the static host name in /etc/hostname file.

Check the hostname.

[root@client ~]# nmcli general hostname
client.itzgeek.com

Change the host name.

[root@client ~]# nmcli general hostname server.itzgeek.com

restart the hostnamed to force the hostnamectl to notice the change in static host name.

[root@client ~]# systemctl restart systemd-hostnamed

4. Edit /etc/hostname

This is the simple, but requires a reboot of server to take an effect.

Note: Use the hostnamectl to change the host name, which fair better than other commands and does not require to update the kernel about the change in host name.