Permanent hostname setup for RHEL7

Step 1

Set the host name on NMTUI tool like following

nmtui

set host name  

then save and exit

Step 2

add the following line in last line of /etc/sysctl.conf

vi  /etc/sysctl.conf

kernel.hostname = hostname.example.com

then save and exit the editor and run the following command

sysctl -p

Step 3

now add the following line that mentioned below in the following file last line  /etc/cloud/cloud.cfg

vi /etc/cloud/cloud.cfg

preserve_hostname: true

save and exit  

then reboot and try again.