Changing hostname is different from RHEL 6 version in RHEL 7. You can use few method to change hostname. I will demonstrate useful and easy method that is hostnamectl command.
Show Current Hostname
[root@localhost ~]# hostname
localhost.localdomainor
[root@localhost ~]# hostnamectl status
Static hostname: localhost.localdomain
Icon name: computer-vm
Chassis: vm
Machine ID: 418f684e1a5c45c9a22f76065c732de3
Boot ID: 9b07d8a45e60437e9ef31164d394ad17
Virtualization: vmware
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 3.10.0-327.36.3.el7.x86_64
Architecture: x86-64
Change Hostname
[root@localhost ~]# hostnamectl set-hostname newname.domain
Show New Value of Hostname
[root@localhost ~]# hostnamectl
Static hostname: newname.domain
Icon name: computer-vm
Chassis: vm
Machine ID: 418f684e1a5c45c9a22f76065c732de3
Boot ID: 9b07d8a45e60437e9ef31164d394ad17
Virtualization: vmware
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 3.10.0-327.36.3.el7.x86_64
Architecture: x86-64
[root@localhost ~]# hostname
newname.domain
Also, you can see new hostname value at /etc/hostname file.
