Depending on your Rendhat 7 installation you may end up with a default hostname localhost.localdomain. This hostname will be shown on various services your new server will offer as well a it will be show on your command prompt such us:

[root@localhost ~]#

To change your hostname simply edit vi /etc/hostname file and inlcude name of your host.

For example to change hostname to "rhel7" the /etc/hostname file will contain:

# cat /etc/hostname
rhel7

To update your command prompt simply re-login and to apply this change system wide execute:

# systemctl restart systemd-hostnamed