mohanpugaz,
I have no knowledge of Centos7, but in Windows 7:
There is a possibility that on shutdown, the system is detecting an error- possibly in shutting down a background program, and this error is triggering an "automatic restart".
To disable automatic restart (Win7) , go to: Control Panel > System > System Protection > Advanced > Startup and Recovery > Settings > System Failure > Uncheck Automatically Restart
Perhaps Centos7 has a similar system protection feature?
Cheers,
BambiBoomZ